The Mark Index

Glass Makers’ Marks: Identify and Date American Pressed, Depression and Art Glass

Most American glass was never marked, and a mark that is there often dates the mold rather than the piece. This guide shows how to read the marks that do exist, which companies used them and when, and how to narrow a date when there is no mark at all. Every date is traced to collector-society research, trademark records and museum sources.

By The Mark Index EditorsSources checked October 6, 202624 makers · 78 marks · 103 sourcesCC BY 4.0
AI illustration: unmarked pressed and Depression-era glass in pink, green, amber, cobalt, yellow and clear on a wooden bench with a brass hand lens

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The short version

Expect no mark. Fostoria used paper labels, most Depression glass is unmarked, and Heisey and Cambridge marked only part of their output.[5][24][33][35][36][43][44][45][46][47][58][59][60][61][62][78][79][80][81] When a mark is there, it usually gives a range, not a year: an H in a diamond is Heisey from 1900 to 1957, and an anchor with an H is Anchor Hocking from June 11, 1938.[5][20][21][22][23][24][25][26][50][51][52][53] Then ask whether the mold outlived the company. Heisey, Cambridge, Westmoreland and Imperial molds were all reused after those firms closed.[8][24][31][32][33][35][36][37][38][39][40][41][42]

Three rules before you trust a glass mark

  1. No mark proves nothing. Paper and foil labels were the norm at Fostoria, Tiffin, Cambridge and Fenton before 1970, and they washed off. A blank base is the usual state of American glass, not a warning sign.[5][24][27][28][29][30][31][32][33][34][78][79][80][81][84][85][86]
  2. The mark dates the mold. Molds were sold with the marks still cut into them. A Westmoreland WG proves a Westmoreland mold, not a piece made before 1984; Summit pressed from Westmoreland, Imperial and Cambridge molds without removing their marks.[32][33][38][39][40][41][42][77]
  3. Read the small changes. Many firms changed their marks in steps. Imperial added letters to its IG, Fenton added a decade numeral under its logo, and Boyd changed its diamond every five years. The small detail is the date.[8][24][27][28][29][30][31][32][33][34][35][36][37][65][66][67]

How to look for a mark on glass

Use raking light
Molded marks on glass are low and clear-on-clear. Tilt the piece under one light source and look for a shadow, or run a fingernail over the base. Check the center of the base, inside the foot, under the lid and on handles.
Know the kinds of mark
Pressed marks are cut into the mold, so they repeat on every piece from it. Acid-etched and sandblasted marks are frosted marks added after the piece was made; Blenko’s sandblasted signature is one. Paper and foil labels carried most company names.[72][73][74][75][76]
Don’t count seams
Pressed glass shows two, three or four mold seams depending on the shape. The Early American Pattern Glass Society says the number of mold lines doesn’t date a piece.[3][4]
Write the mark down exactly
Record each letter, the shape around it, any numeral nearby and where it sits. “I over G with an L” and “I over G” are fifty years apart at Imperial.[8][24][31][32][33][35][36][37]
AI illustration: two hands hold a plain pale green glass plate up to a window to look for a mark in the light

Narrow the date

Pick what kind of glass it is, then the mark if there is one. The tool combines the ranges and shows which clue sets each limit. Only marks and eras with at least two independent sources are included.

What kind of glass is it?
Mark molded, etched or blasted into the glass pick one

A tool can’t see a reused mold. If the answer looks too old for the color or finish, read the molds and reissues notes for that maker.

The one-page cheat sheet

Every two-sourced mark on one sheet of paper, with the reading rules and the eras. Print it for a show, a club meeting, a classroom or a reference desk.

Download the PDFOpen to print

Attribution line: “Glass Makers’ Marks” by The Mark Index (https://themarkindex.com/glass-makers-marks/), licensed under CC BY 4.0.

Glass marks and eras at a glance

“About” marks a soft limit. The superscript numbers lead to the sources; “Maker” leads to the full entry in the maker table.

Mark or kind of glassDate rangeMaker or what to watch forSources
Kinds of glass and their eras
Pressed (machine-molded) glass of any kind1820s onward (hand-lever presses perfected in the U.S. in the 1820s)Glass pressed into a metal mold by a hand-operated press was perfected in the United States in the 1820s, so pressed tableware cannot be earlier than that decade.Details [1][2]
Early American Pattern Glass (EAPG): pressed pattern tableware made as matching setsabout 1850 to 1910 (some writers extend to 1920)Collector societies date Early American Pattern Glass to about 1850-1910, with most made in the 1880s; one EAPGS-hosted chart extends the era to 1920.Details [1][3][4][5]
Iridized pressed "carnival" glass (classic or prime period, U.S.)autumn 1907 (Fenton) to the late 1920s; Diamond Glass-Ware to its 1931 closureFenton introduced iridized pressed glass in 1907 and Northwood followed in 1908; the classic U.S.Details [6][7][8]
Iridescent "stretch glass" (onion-skin or cobweb iridescence, little or no pattern, no pontil mark)about 1912 to the early 1930s; Fenton again 1975-76 and 1980-2011Stretch glass was made by nine U.S.Details [9][10][11]
Machine-made "Depression glass" (mass-produced pressed colored or crystal tableware)late 1920s to about 1940 is the core; definitions run from the early 1920s to the end of World War II, some patterns into the 1950sDepression glass is machine-pressed, mass-produced tableware; the core period is the late 1920s through the 1930s, but collector definitions range from the early-to-mid 1920s to the end of World War II, and some patterns stayed in production into the 1950s..Details [12][13][14][15][16]
Iridized "carnival" glass in new colors, reissued patterns or souvenir/club pieces1960s onward (Fenton from 1970 per NDGA)Interest from collectors from the 1950s led Fenton and Imperial to make carnival glass again from the 1960s, first from old molds and later from new ones; other makers (Indiana, L.G.Details [7][8]
Uranium ("vaseline"/canary) glass that glows green under UV lightU.S. production about 1830s-1942/43 (natural uranium) and from about 1958-59 (depleted uranium); none made about 1943-1958Boyd, Mosser, Summit and Fenton were among later makers..Details [17][18][19]
Marks pressed, etched or blasted into the glass
Capital H inside a vertical (upright) diamond, pressed into the glass ("Diamond H")about 1900 to 1957A. H. Heisey & Co.Maker [5][20][21][22][23][24][25][26]
'Fenton' in script inside an oval1970 onFenton Art Glass CompanyMaker [24][27][28][29][30][31][32][33][34]
Small numeral under/near the logo giving the decade: 8 = 1980s, 9 = 1990s, 0 = 2000-2009, 1 = 2010sabout 1980 onFenton Art Glass CompanyMaker [24][27][28][29][30][31][32][33][34]
Script F inside a vertical oval (on glass made from molds bought from other companies, e.g. McKee, Imperial, L. G. Wright)about 1983 onFenton Art Glass CompanyMaker [24][27][28][29][30][31][32][33][34]
NUCUT (Nu-cut) pressed into imitation cut glass1911 to about 1932Imperial Glass Company (Imperial Glass Corporation from 1931 reorganization)Maker [8][24][31][32][33][35][36][37]
NUART (Nu-art) on iridescent ware such as some Homestead and Chrysanthemum plates1912 onImperial Glass Company (Imperial Glass Corporation from 1931 reorganization)Maker [8][24][31][32][33][35][36][37]
"Imperial Iron Cross" – the word IMPERIAL split into four parts (IM/PE/RI/AL) within a cross or four squaresabout 1913 to about 1951Imperial Glass Company (Imperial Glass Corporation from 1931 reorganization)Maker [8][24][31][32][33][35][36][37]
IG monogram: an I superimposed on a G (can look like a dollar sign or treble clef; G often read as C)1951 to about 1977Imperial Glass Company (Imperial Glass Corporation from 1931 reorganization)Maker [8][24][31][32][33][35][36][37]
LIG (L added to the IG monogram) – Lenox periodabout 1973 to 1981Imperial Glass Company (Imperial Glass Corporation from 1931 reorganization)Maker [8][24][31][32][33][35][36][37]
ALIG (A added to LIG) – Arthur Lorch period1981 to about 1982Imperial Glass Company (Imperial Glass Corporation from 1931 reorganization)Maker [8][24][31][32][33][35][36][37]
Capital W inside a Pennsylvania keystoneabout 1910 to about 1929Westmoreland Glass Company (Westmoreland Specialty Company until 1920s)Maker [32][33][38][39][40][41][42]
WG monogram (W superimposed over G)about 1946 to 1984Westmoreland Glass Company (Westmoreland Specialty Company until 1920s)Maker [32][33][38][39][40][41][42]
WESTMORELAND in a semicircle above a W (Grossman-era mark)about 1981 to 1984Westmoreland Glass Company (Westmoreland Specialty Company until 1920s)Maker [32][33][38][39][40][41][42]
NEARCUT (one or two words) cut into the mold and pressed into imitation-cut glass1904 to about 1922The Cambridge Glass CompanyMaker [5][33][35][36][43][44][45][46][47]
Capital C inside an equilateral triangle (Triangle C), molded; large (8 mm sides) then small (5 mm)about 1923 to about 1937The Cambridge Glass CompanyMaker [5][33][35][36][43][44][45][46][47]
Underlined capital N inside a circle (earlier with two concentric circles); also underlined N aloneabout 1902 to 1925H. Northwood & Co. (Northwood Glass Co.), Wheeling factoryMaker [8][32][33][48][49]
Anchor with a capital H superimposed (anchor-over-H)1938 to about 1980Anchor Hocking Glass Corp. (Anchor Hocking Corp. from 1969)Maker [50][51][52][53][54][55][56][57]
FIRE-KING (brand name, molded in base of ovenware, mugs, bowls)1941 to about 2000Anchor Hocking Glass Corp. (Anchor Hocking Corp. from 1969)Maker [50][51][52][53][54][55][56][57]
Stylized anchor inside a round-cornered rectangle ("boxed anchor")1977 to about 2000Anchor Hocking Glass Corp. (Anchor Hocking Corp. from 1969)Maker [50][51][52][53][54][55][56][57]
Plain anchor (no H)2009 onAnchor Hocking Glass Corp. (Anchor Hocking Corp. from 1969)Maker [50][51][52][53][54][55][56][57]
Capital H above a smaller A ("H over A")1923 to about 1964Hazel-Atlas Glass Co.Maker [24][45][58][59]
Capital F inside a shieldabout 1932 to about 1979Federal Glass Co.Maker [24][60][61][62]
Capital J inside a square (Box-J)1940 to about 1945Jeannette Glass Co. (Jeannette Corp. from 1970)Maker [24][63][64]
Capital B inside a diamond, no lines1978 to 1983Boyd's Crystal Art GlassMaker [65][66][67]
B in a diamond with three surrounding lines1993 to 1998Boyd's Crystal Art GlassMaker [65][66][67]
Capital D inside a circleabout 1967 to 1972Degenhart's Crystal Art Glass (Crystal Art Glass Co.)Maker [45][65][67][68]
Capital D inside a heart outlineabout 1972 to 1978Degenhart's Crystal Art Glass (Crystal Art Glass Co.)Maker [45][65][67][68]
PYREX (all capital letters), with TRADE MARK / REG. U.S. PAT. OFF. / MADE IN U.S.A.1915 to about 1998Corning Glass Works (PYREX brand); World Kitchen/Corelle Brands/Instant Brands licensees after 1998Maker [55][69][70][71]
"Blenko" signature on the base1958 to about 1961Blenko Glass Co. (Eureka Art Glass Co. at first)Maker [72][73][74][75][76]
Small sandblasted Blenko signature with year of manufacture2001 onBlenko Glass Co. (Eureka Art Glass Co. at first)Maker [72][73][74][75][76]
Capital V inside a circle (for Vogelsong)about 1972 to about 2006Summit Art Glass Co.Maker [39][77]

American glass makers and their marks

Marks are described in words; we don’t reproduce them. A one source flag means we found only one source for that mark’s dates, so it stays out of the tool and the cheat sheet until a second turns up. Where sources disagree, the dating tip says so.

24 of 24 makers
MakerMarks, in words, and years usedDating tipsSources
A. H. Heisey & Co.Newark, Ohio. 1896-1957
  • Capital H inside a vertical (upright) diamond, pressed into the glass ("Diamond H")about 1900 to 1957 molded/pressed
  • Paper labels reading Heisey or Heisey's (Diamond H also applied as a label)until 1957 paper label
  • HCA plus year of reissue and a maker letter/symbol, on reissues from Heisey molds commissioned by Heisey Collectors of Americaone sourcedates not established molded/pressed

A Diamond H with an H in an upright diamond points to Heisey, but no mark does not rule Heisey out: glass made before November 1900 and most blown pieces were never marked.

Unmarked Glass made April 1896 to November 1900 is unmarked; from the 1920s the mark grew smaller, was sometimes omitted or ground off, and blown items were usually unmarked; paper labels were often washed off.

Molds later Imperial Glass bought Heisey's molds after the 1957 closing and made 'Heisey by Imperial' until 1984; in 1985 Heisey Collectors of America acquired most of those molds and has had reissues (marked HCA) made by Fenton, Dalzell-Viking and Mosser. Whether every Imperial-made Heisey-mold piece carried an Imperial mark was not confirmed in saved sources.

[5][20][21][22][23][24][25][26]
Fenton Art Glass CompanyMartins Ferry, Ohio (1905); Williamstown, West Virginia (from 1907). 1905-2011 (traditional glassmaking)
  • Paper or foil labels (no molded mark)until about 1970 paper label
  • 'Fenton' in script inside an oval1970 on molded/pressed
  • Small numeral under/near the logo giving the decade: 8 = 1980s, 9 = 1990s, 0 = 2000-2009, 1 = 2010sabout 1980 on molded/pressed
  • Script F inside a vertical oval (on glass made from molds bought from other companies, e.g. McKee, Imperial, L. G. Wright)about 1983 on molded/pressed
  • O V G monogram (letters overlapping vertically) – Olde Virginia Glass line sold by Fentonone sourceabout 1970 on molded/pressed

An oval script Fenton logo means 1970 or later; look for a tiny 8, 9, 0 or 1 near it to get the decade, and a script F in an oval means a Fenton piece made in another company's old mold.

Unmarked Before 1970 Fenton relied on removable paper or foil labels, so most earlier Fenton is now unmarked.

Molds later Fenton reused molds bought from Diamond Glass-Ware, Paden City, Verlys, U.S. Glass, McKee, Imperial and L. G. Wright; after traditional glassmaking stopped in 2011, Mosser Glass made pieces from Fenton molds for the Fenton Gift Shop.

[24][27][28][29][30][31][32][33][34]
Fostoria Glass CompanyFostoria, Ohio (1887); Moundsville, West Virginia (from 1891). 1887-1986
  • Paper labels (no regular molded mark)until about 1986 paper label

Do not expect a molded mark on Fostoria; identification rests on pattern and shape, and American-pattern pieces can be later Lancaster Colony/Indiana Glass production from the same molds.

Unmarked Fostoria marked its glass with paper labels, which are usually lost, so most Fostoria is found unmarked.

Molds later Lancaster Colony bought Fostoria in 1983 and closed it in 1986; the American pattern continued to be made from Fostoria molds by its Indiana Glass subsidiary (sold as American Whitehall), and Lancaster contracted other factories for some American pieces.

[5][78][79][80][81]
Imperial Glass Company (Imperial Glass Corporation from 1931 reorganization)Bellaire, Ohio. 1902-1984
  • NUCUT (Nu-cut) pressed into imitation cut glass1911 to about 1932 molded/pressed
  • NUART (Nu-art) on iridescent ware such as some Homestead and Chrysanthemum plates1912 on molded/pressed
  • "Imperial Iron Cross" – the word IMPERIAL split into four parts (IM/PE/RI/AL) within a cross or four squaresabout 1913 to about 1951 molded/pressed
  • IG monogram: an I superimposed on a G (can look like a dollar sign or treble clef; G often read as C)1951 to about 1977 molded/pressed
  • LIG (L added to the IG monogram) – Lenox periodabout 1973 to 1981 molded/pressed
  • ALIG (A added to LIG) – Arthur Lorch period1981 to about 1982 molded/pressed
  • NI superimposed ('New Imperial')one sourceabout 1981 on molded/pressed

Read the letters around the IG: plain IG is 1951 into the 1970s, an added L means the Lenox years (1970s-1981), and an added A (ALIG) means 1981-82.

Unmarked Most early colored and carnival Imperial is unmarked, and Imperial did not necessarily mark long-running lines such as Candlewick and Cape Cod.

Molds later Imperial bought Heisey's molds (1958) and Cambridge's assets (1960) and sold 'Heisey by Imperial' and 'Cambridge by Imperial'; after Imperial's 1984 bankruptcy most Heisey molds went to Heisey Collectors of America and Cambridge molds to the National Cambridge Collectors; Fenton also bought Imperial molds and marks them with a script F in an oval.

[8][24][31][32][33][35][36][37]
Westmoreland Glass Company (Westmoreland Specialty Company until 1920s)Grapeville, Pennsylvania. 1889-1984
  • Capital W inside a Pennsylvania keystoneabout 1910 to about 1929 molded/pressed
  • WG monogram (W superimposed over G)about 1946 to 1984 molded/pressed
  • WESTMORELAND in a semicircle above a W (Grossman-era mark)about 1981 to 1984 molded/pressed
  • Paper or foil labels, usually reading Westmoreland Glass in a circle around the keystone or WGuntil 1984 paper label

A WG or WESTMORELAND mark proves the mold was Westmoreland's, not that the piece was made before 1984, because molds were sold with the marks still in them.

Unmarked Not all Westmoreland is marked; earlier ware often was not, and worn mold marks were left unrepaired, so genuine pieces can lack the WG.

Molds later After closure on January 1, 1984 the molds were sold to other firms and individuals who did not always remove the Westmoreland marks; Plum Glass (from 1985) used Westmoreland molds and marked glass with a P or PG in a keystone, often alongside the Westmoreland mark.

[32][33][38][39][40][41][42]
The Cambridge Glass CompanyCambridge, Ohio. 1901-1958 (production from May 1902; closed 1954, reopened 1955)
  • NEARCUT (one or two words) cut into the mold and pressed into imitation-cut glass1904 to about 1922 molded/pressed
  • Capital C inside an equilateral triangle (Triangle C), molded; large (8 mm sides) then small (5 mm)about 1923 to about 1937 molded/pressed
  • Triangle C paper labels (yellow lettering on black; with TRADEMARK, later GENUINE, then GENUINE HAND MADE)one sourceabout 1927 to 1937 paper label
  • Oval paper label: Cambridge in Old English type with GENUINE HAND MADE above and MADE IN U.S.A. below, gold on blackone source1938 to 1954 paper label

A Triangle C dates a piece to about 1923-1937; Cambridge lines introduced later, such as Caprice and Pristine, are not known with the molded mark.

Unmarked Much Cambridge glass was never marked; the molded Triangle C was used only on some items and most pieces relied on paper labels that washed off.

Molds later Imperial Glass acquired Cambridge's assets (1960 per the Imperial society) and sold 'Cambridge by Imperial'; after Imperial's 1984 closure the Cambridge molds were bought mostly by the National Cambridge Collectors.

[5][33][35][36][43][44][45][46][47]
H. Northwood & Co. (Northwood Glass Co.), Wheeling factoryWheeling, West Virginia (earlier Northwood works at Martins Ferry, Ohio; Ellwood City and Indiana, Pennsylvania). 1902-1925 (Wheeling; BRG gives receivership 1926)
  • Underlined capital N inside a circle (earlier with two concentric circles); also underlined N aloneabout 1902 to 1925 molded/pressed
  • 'Northwood' in script (molded signature)one sourcedates not established molded/pressed

Check that the N is underlined and fully circled: an N with a broken circle, a 'wonky' N, or a heavy N with no circle or underline points to later look-alikes rather than Northwood.

Unmarked Not all Northwood carnival and decorative glass was marked, though a good percentage of Wheeling production was.

Molds later Look-alike N marks: L. G. Wright used a similar N until a lawsuit stopped it; American Carnival Glass Assn. registered an underlined N in a circle in 1970; Mosser pieces (c. 1970s) carry an N in a partial circle; Far East fakes have a heavy N with no circle; in the 1990s a grandson revived the Northwood name with glass made by Fenton.

[8][32][33][48][49]
Dugan Glass Company (1904-1913), then Diamond Glass-Ware Company (1913-1931)Indiana, Pennsylvania. 1904-1931
  • Capital D inside a diamond ("Diamond D")one sourcedates not established molded/pressed

Most Dugan-Diamond carnival is unmarked and was long credited to Northwood; peach opalescent carnival points strongly to this factory.

Unmarked Dugan did not usually mark its carnival glass, and some pieces from former Northwood molds were made after the Northwood mark was removed.

Molds later After the 1931 fire Fenton obtained a few Diamond Glass-Ware molds.

[8][31][33][45][82][83]
United States Glass Co. Factory R, Tiffin (later Tiffin Art Glass Co. / Tiffin Glass Co.)Tiffin, Ohio. 1889-1980 (furnaces shut May 1, 1980)
  • Paper label: letters USG intertwined in a gold shielduntil 1927 paper label
  • Gold paper label: TIFFIN over a large T in a shield (Tiffin shield)1927 to about 1980 paper label
  • Tiffin shield trademark applied as an acid stampone sourcedates not established acid-etched
  • U over S monogram of the United States Glass Co., molded (rare)one sourcedates not established molded/pressed

Tiffin relied on paper labels: a USG shield label means U.S. Glass marketing before September 1927, a TIFFIN-on-T shield label means 1927 or later.

Unmarked Tiffin was identified mainly by paper labels, so most pieces are unmarked once the label is gone.

Molds later After production ended in 1980 the molds were dispersed; Summit Art Glass acquired the Tiffin shield trademark mold, which the Tiffin Glass Collectors Club bought in 1991 and has used for colored logo pieces. Tiffin also made Duncan & Miller patterns from 1955 using Duncan molds.

[33][84][85][86]
Duncan & Miller Glass CompanyWashington, Pennsylvania. 1893-1955 (Duncan & Miller name from 1900; family firm traced to 1865/1874 in Pittsburgh)
  • No molded mark recorded in our sources.

Duncan & Miller patterns kept being made at Tiffin, Ohio after 1955, and Fostoria made look-alike opalescent glass, so pattern alone does not prove a Washington, Pa. origin.

Molds later When the Washington, Pa. factory closed in June 1955 the molds went to the United States Glass Company at Tiffin, Ohio, whose Duncan & Miller Division continued Duncan patterns (Wikipedia says until 1980).

[86][87][88][89][90]
Anchor Hocking Glass Corp. (Anchor Hocking Corp. from 1969)Lancaster, Ohio. 1937-present
  • Anchor with a capital H superimposed (anchor-over-H)1938 to about 1980 molded/pressed
  • FIRE-KING (brand name, molded in base of ovenware, mugs, bowls)1941 to about 2000 molded/pressed
  • ANCHORGLASS (one word; mostly on foil labels, embossed on Royal Ruby bottles)1945 to about 1950 foil label
  • Stylized anchor inside a round-cornered rectangle ("boxed anchor")1977 to about 2000 molded/pressed
  • Plain anchor (no H)2009 on molded/pressed

The original anchor-over-H was first used June 11, 1938, the boxed anchor September 14, 1977, and the plain anchor (no H) March 16, 2009, per USPTO records, so the style of anchor brackets the age of a marked piece.

Unmarked Whitten notes that Anchor Hocking's Early American Prescut pattern (1960-1999) is mostly, if not all, unmarked.

Molds later A redrawn anchor-with-H mark was registered in 2018 (first use 2017), so an anchor-H on a piece does not by itself prove pre-1977 manufacture.

[50][51][52][53][54][55][56][57]
Hazel-Atlas Glass Co.Wheeling, West Virginia. 1902-1964
  • Capital H above a smaller A ("H over A")1923 to about 1964 molded/pressed
  • CCC (three nested Cs, Continental Can)one sourceabout 1957 to about 1964 molded/pressed

On Hazel-Atlas tableware such as tumblers, the H-over-A mark dates from 1923 at the earliest; from 1957 to 1964 some new molds carried Continental Can's CCC mark instead (Whitten).

Unmarked Whitten: most items in Hazel-Atlas Depression-era pattern sets were not marked.

[24][45][58][59]
Federal Glass Co.Columbus, Ohio. 1900-1979
  • Capital F inside a shieldabout 1932 to about 1979 molded/pressed

Federal's F-in-a-shield is a tableware mark (the 1944 registration excluded bottles and jars), and Whitten reports it on 1976 Bicentennial pieces, so it was not retired in 1958.

Unmarked Whitten: Federal made large quantities of Depression glass in the 1920s-1940s, most of it unmarked.

Molds later Whitten: the Madrid pattern (1932-1939) was reissued by Federal in 1976.

[24][60][61][62]
Jeannette Glass Co. (Jeannette Corp. from 1970)Jeannette, Pennsylvania. 1898-1983
  • Capital J inside a square (Box-J)1940 to about 1945 molded/pressed
  • Capital J inside a triangledates not established molded/pressed

Jeannette made only tableware from 1924 until it closed in 1983 (BRG), and its J-in-a-triangle mark is disputed with D.C. Jenkins Glass Co., so that mark alone is not proof of Jeannette.

Molds later NDGA (Eickholt): Jeannette reissued its Anniversary pattern with an iridescent finish in the late 1960s to mid-1970s, so iridescent Anniversary is not Depression-era.

[24][63][64]
Indiana Glass Co. (Lancaster Colony subsidiary from 1957/1961)Dunkirk, Indiana. 1907-2002 (Dunkirk glassmaking)
  • LCC (Lancaster Colony Corporation) with "Indiana Glass / Made in U.S.A."one sourceabout 1957 on molded/pressed

Whitten says the round mold circle on the back of Indiana Glass hen-on-nest covers is a mold feature, not a maker's mark, and nearly all Indiana Glass is unmarked.

Unmarked Whitten: almost all Indiana Glass glassware is unmarked; a few pieces carry LCC.

Molds later NDGA (Eickholt): Indiana sold reproductions of older patterns through the Tiara party plan and reissued patterns such as Diamond Point and Pretzel.

[24][91][92]
L. E. Smith Glass Co.Mount Pleasant, Pennsylvania. 1907-c. 2010 (closing date disputed)
  • Cursive capital S (resembles a treble clef) or plain capital Sone sourceabout 1960 on molded/pressed
  • S with small G and C inside its curvesone sourcedates not established molded/pressed
  • S inside a circleone sourceabout 1990 on molded/pressed

L.E. Smith marked only a small share of its output, so an unmarked piece cannot be ruled out as L.E. Smith (Whitten); the cursive S mark dates from the 1960s or later.

Unmarked Whitten: the cursive S was used on only a very small percentage of L.E. Smith's output.

Molds later Whitten: wholesaler Rosso had glass made by several firms including L. E. Smith; such pieces carry Rosso's R-in-keystone mark.

[32][39][93]
Boyd's Crystal Art GlassCambridge, Ohio. 1978-2014 (Owl Depot says factory closed 2013)
  • Capital B inside a diamond, no lines1978 to 1983 molded/pressed
  • B in a diamond with one line beneathone source1983 to 1988 molded/pressed
  • B in a diamond with lines above and belowone source1988 to 1993 molded/pressed
  • B in a diamond with three surrounding lines1993 to 1998 molded/pressed
  • B in a diamond completely enclosed in a rectangleone source1998 to 2003 molded/pressed
  • B in a diamond with an extra B in the top-left triangleone source2003 to 2008 molded/pressed
  • B in a diamond with a B and an O addedone source2008 to 2014 molded/pressed

Boyd changed its B-in-a-diamond mark every five years by adding lines or letters, so the exact variant dates a piece to a five-year window (Glass Encyclopedia; Whitten).

Molds later Boyd bought the Degenhart factory and molds in 1978 (except 15 molds Elizabeth Degenhart retired), removed the D-in-heart and marked the reused molds with Boyd's B in a diamond. When Boyd closed in 2014 its molds were sold with the B mark removed, so later pressings from Boyd molds may be unmarked.

[65][66][67]
Degenhart's Crystal Art Glass (Crystal Art Glass Co.)Cambridge, Ohio. 1947-1978
  • Capital D inside a circleabout 1967 to 1972 molded/pressed
  • Capital D inside a heart outlineabout 1972 to 1978 molded/pressed

Degenhart's D was hand-stamped into each piece while it was hot in the mold, so marks vary in shape and crispness (Owl Depot).

Unmarked Whitten: glassware made by Degenhart from 1947 to 1964 was evidently unmarked.

Molds later When Boyd bought the factory in 1978 it reused Degenhart molds but removed the D-in-heart and substituted its B in a diamond (Glass Encyclopedia; Whitten). Degenhart's owl was itself a copy of Westmoreland's owl, which lacks the D mark (Owl Depot).

[45][65][67][68]
Libbey Glass Co. (Libbey Glass, Inc.)Toledo, Ohio. 1888-present in Toledo (New England Glass Co. roots 1818)
  • Spread-wing eagle with "Libbey Cut Glass Toledo, Ohio" (cut glass)one source1892 to 1896 acid-etched
  • "Libbey" in script with a sword beneath (cut glass)one source1896 to 1906 acid-etched
  • "Libbey" in script without sword, L and y usually connected (cut glass)one source1906 on acid-etched
  • Cursive capital L inside a double ringone sourceabout 1924 on molded/pressed
  • Cursive capital L inside a broken (three-segment) circleone source1937 on molded/pressed
  • Cursive capital L inside a plain circleone source1955 on molded/pressed
  • Plain cursive capital L (no circle)one sourcedates not established molded/pressed

On Libbey tumblers, the cursive L is often faint and can look like a short curly hair, a cursive Q or a looped numeral 2 embedded in the base (Whitten).

Unmarked Whitten: not all Libbey glassware is marked, although much of it is.

[94][95][96]
Corning Glass Works (PYREX brand); World Kitchen/Corelle Brands/Instant Brands licensees after 1998Corning, New York. 1875-present (Corning); PYREX brand from 1915
  • PYREX (all capital letters), with TRADE MARK / REG. U.S. PAT. OFF. / MADE IN U.S.A.1915 to about 1998 molded/pressed
  • pyrex (lowercase) on U.S.-market consumer wareone sourceabout 1998 on molded/pressed
  • Flame logo with item number and size (Pyrex Flameware)one sourceabout 1936 to about 1979 molded/pressed

Older borosilicate PYREX is generally marked in capitals, while the post-1998 soda-lime ware for the U.S. market is usually marked in lowercase "pyrex" (Whitten).

Molds later Whitten: after 1998 the PYREX consumer brand was assigned to World Kitchen (later Corelle Brands, then Instant Brands), and the U.S. formula changed to tempered soda-lime glass.

[55][69][70][71]
Steuben Glass Works (Corning division from 1918; Steuben Glass, Inc. from 1933)Corning, New York. 1903-2011
  • Fleur-de-lis with "Steuben" in a bannerone source1903 to 1933 acid-etched
  • STEUBEN in block lettersone source1903 to 1933 acid-etched
  • Steuben in scriptone sourceabout 1928 to about 1932 acid-etched
  • Aurene / Steuben Aurene with shape numberone sourceabout 1904 on engraved/signature
  • Single letter S scratched with a diamond pointone source1932 on engraved/signature
  • Steuben signature used by Schottenstein ownersone source2008 to 2011 engraved/signature

CSGA notes that much Carder-era Steuben was sold with only a paper label and that several Steuben marks have been faked, so a mark is not proof by itself.

Unmarked CSGA (quoting a Corning Leader history): much Carder-period glass was sold only with a paper label.

Molds later CSGA: forged fleur-de-lis, block-letter and Frederick Carder signatures exist.

[97][98][99][100]
Blenko Glass Co. (Eureka Art Glass Co. at first)Milton, West Virginia. 1921-present at Milton
  • Silver foil hand-shaped "Blenko Handcraft" stickerone sourceabout 1930 to 1982 foil label
  • Hand-signed "Blenko" (William Blenko Jr.)one source1958 to 1958 acid-etched
  • "Blenko" signature on the base1958 to about 1961 sandblasted
  • Block B sticker (orange ball and pipe design, by John Nickerson)one source1982 to about 1999 paper label
  • Small sandblasted Blenko signature with year of manufacture2001 on sandblasted

A Blenko signature with no year was used mainly from 1958 to about 1960-1961; from 2001 the sandblasted signature includes the year (Blenko Glass Collectors; Atomic Ranch). Today Blenko also sells a sandblasted presidential signature as an add-on, so a signature alone does not date a piece.

Unmarked Whitten: very few Blenko articles were marked in the glass itself; labels were usual.

Molds later Blenko Glass Collectors: Blenko made Williamsburg Restoration reproductions from 1936 to 1966, and reproductions sold through Neiman Marcus in 2001 were etched on the bottom.

[72][73][74][75][76]
Mosser Glass, Inc.Cambridge, Ohio. 1971-present (glassmaking from 1959)
  • Capital M inside a circle (the M may look like an upside-down W)one sourceabout 1971 on molded/pressed
  • Capital M inside an outline of the state of Ohioone sourcedates not established molded/pressed

Mosser's line uses molds acquired from Viking, L.G. Wright and Cambridge Glass, so a Mosser piece can repeat an older company's design; look for the M mark (Mosser; Whitten).

Molds later Mosser (company history) says its line includes timeless classics acquired from Viking, L.G. Wright and Cambridge Glass; Whitten documents Mosser's colored versions of the 1880s Bryce Brothers Robin in Tree mug.

[32][101][102]
Summit Art Glass Co.Akron, then Ravenna, Ohio. 1972-2006
  • Capital V inside a circle (for Vogelsong)about 1972 to about 2006 molded/pressed

Summit marked only some of its glass with a V in a circle (others had a sticker), and it pressed from other companies' molds without removing their marks (Carnival Glass Clubs; Whitten).

Unmarked Whitten: only a percentage of Summit glass carries the V-in-a-circle mark.

Molds later Summit acquired molds from St. Clair, Westmoreland, Imperial and Cambridge and did not always remove the old marks, so a piece marked Westmoreland may have been pressed by Summit (Carnival Glass Clubs).

[39][77]

Dates that are often repeated wrong

  • Imperial’s late marks run IG, then LIG, then ALIG. The L was added in the Lenox years (1973 to 1981) and the A in the Arthur Lorch period (1981 to 1982). Lists that put ALIG before LIG have them reversed.[8][24][31][32][33][35][36][37]
  • Anchor Hocking’s anchor-H starts June 11, 1938, per the USPTO record and the Bottle Research Group, not with the 1937 merger. A redrawn anchor-H was registered with first use in 2017, so the mark only sets a floor.[50][51][52][53]
  • Heisey’s Diamond H first appears in an 1900 advertisement; 1901 is the trademark approval. Glass made before about November 1900 is unmarked.[5][20][21][22][23][24][25][26]
  • Federal’s F in a shield didn’t end in 1958. It appears on 1976 Bicentennial pieces, and Federal made glass until 1979.[60][61][62]
  • Cambridge’s Triangle C is from the 1920s, not 1902. It first appears in a December 1922 advertisement and was used to about 1937. Cambridge closed in 1954, reopened in 1955 and closed for good in 1958.[5][33][35][36][43][44][45][46][47]
  • Northwood’s underlined N in a circle dates from 1902 in the sources we found, not 1905 or 1906: two circles to 1910, one circle to 1925.[8][32][33][48][49]
  • Jeannette’s J in a square has a trademark claim of first use in 1940, not the 1910s or 1920s.[24][63][64]

When molds outlive the company

Glass molds are expensive iron tools that last for generations, so they were sold, borrowed and reused. That is the single biggest trap in dating marked glass.

  • Heisey. Imperial bought Heisey’s molds after the 1957 closing and sold “Heisey by Imperial.” In 1985 Heisey Collectors of America acquired most of them; its reissues are marked HCA and come in colors Heisey never used.[5][20][21][22][23][24][25][26]
  • Cambridge. Imperial acquired Cambridge’s assets and sold “Cambridge by Imperial.” After Imperial closed in 1984, most Cambridge molds went to the National Cambridge Collectors.[5][8][24][31][32][33][35][36][37][43][44][45][46][47]
  • Westmoreland. After the January 1984 closing the molds were sold, often with the Westmoreland marks still in them. Plum Glass used Westmoreland molds and added a P or PG in a keystone.[32][33][38][39][40][41][42]
  • Degenhart and Boyd. Boyd bought the Degenhart factory in 1978, removed the D in a heart and put its own B in a diamond on the reused molds. When Boyd closed, its molds were sold with the B removed.[45][65][66][67][68]
  • Northwood look-alikes. L. G. Wright used a similar N until a lawsuit stopped it, a collectors’ association registered an underlined N in a circle in 1970, and Mosser pieces carry an N in a partial circle.[8][32][33][48][49]
  • Fostoria’s American pattern continued from Fostoria molds at Indiana Glass after Lancaster Colony bought Fostoria in 1983.[5][78][79][80][81]

Eras and kinds of glass

Pressed glass
Hand-lever pressing into a metal mold was perfected in the United States in the 1820s, so no pressed tableware is earlier than that decade.[1][2]
Early American Pattern Glass
Matching pressed sets, dated by collector societies to about 1850 to 1910, most from the 1880s. One chart hosted by the Early American Pattern Glass Society runs the era to 1920.[1][3][4][5]
Carnival glass
Fenton introduced iridized pressed glass in 1907 and Northwood followed in 1908. The classic period ran to the late 1920s, and volume production had virtually stopped by the early 1930s. The name “carnival glass” came only in the 1950s; makers sold it as Iridill, Golden Iris or Venetian Art.[6][7][8] Fenton and Imperial made it again from the 1960s, first from old molds, which is why old and new are easy to confuse.[7][8]
Stretch glass
Onion-skin iridescence with little or no pattern, made by nine U.S. companies from about 1912 to the early 1930s and again by Fenton in 1975 to 1976 and about 1980 to 2011. It was molded, never free-blown, so it has no pontil mark.[9][10][11]
Depression glass
Machine-pressed, mass-produced tableware. The core years are the late 1920s through the 1930s, but even the National Depression Glass Association’s own pages give ranges from the early 1920s to the end of World War II, and some patterns stayed in production into the 1950s.[12][13][14][15][16]
Elegant glass
Hand-made tableware of the same years from Heisey, Cambridge, Fostoria and similar houses: fire-polished seams and often ground bases, where machine-made Depression glass shows distinct seams, straw marks and bubbles. It is a maker clue, not a date clue.[4][13][14][103]
Uranium (“vaseline”) glass
Glass that glows green under ultraviolet light. U.S. production stopped during World War II, about 1943, and resumed about 1958 to 1959 with depleted uranium. A glowing piece is either before about 1943 or after about 1958; the glow alone can’t tell you which.[17][18][19]
Fire-King and Pyrex
Anchor Hocking claimed first use of FIRE-KING on January 30, 1941; sources disagree on whether the line ended in the late 1970s or ran to 2000.[52][54][55] Corning claimed first use of PYREX on May 20, 1915; older borosilicate ware is marked in capitals.[55][69][70]

Clubs, museums and references: current addresses

Collector societies and museums are where the real mark knowledge lives: catalogs, reprints, mold histories and people who will look at a photo. Many glass links on older club and library pages have broken because clubs moved, merged or closed. Every address below was opened on October 6, 2026. Struck-through addresses are old ones that no longer work.

47 of 47 entries
Organization or resourceCurrent addressWhat it isOld address
Fostoria Glass Society of America / Fostoria Glass MuseumMuseumfostoriaglass.orgSociety and museum at 511 Tomlinson Ave., Moundsville, West Virginia, for glass of the Fostoria Glass Company (1887-1986).Unchanged
Heritage Glass Museum (Glassboro, NJ)Museumheritageglassmuseum.orgVolunteer-run, free-admission museum at 25 High Street East, Glassboro, New Jersey, preserving southern New Jersey glassmaking history.http://www.fieldtrip.com/nj/98817468.htm
Museo dell'Arte Vetraria Altarese (Altare Glass Museum)Museummuseodelvetro.orgGlass art museum in Altare (Savona), Italy, with exhibitions, a specialist library and the Altare Glass Fest.http://www.liguriapocket.com/tappe.aspx?ID=TAP0000065&L=ENG
Museum of American Glass at WheatonArtsMuseumwheatonarts.orgMuseum of American Glass at WheatonArts in Millville, New Jersey, alongside artist studios and the Creative Glass Fellowship Program.Unchanged
National Cambridge Collectors / National Museum of Cambridge GlassMuseumcambridgeglass.orgAll-volunteer nonprofit collectors group dedicated to the art and history of Cambridge Glass; operates the National Museum of Cambridge Glass and a virtual museum.http://www.cambridgeglass.org/museum.phphttp://wwwcambridgeglass.org/
National Depression Glass AssociationMuseumndga.netCollectors association and free-admission museum for American-made glassware with an emphasis on the Depression era.Unchanged
National Duncan Glass Society / Duncan & Miller Glass MuseumMuseumduncan-miller.orgCollectors society running the Duncan & Miller Glass Museum in Washington, Pennsylvania.http://www.duncanmiller.net
National Greentown Glass Association (Greentown Glass Museum)Museumgreentownglass.org/museumNonprofit collectors association for glass made by the Indiana Tumbler & Goblet works in Greentown, Indiana, 1894-1903, with a museum page on its site.http://www.greentownglass.org/museum_news.php
National Heisey Glass Museum (Heisey Collectors of America)Museumheiseymuseum.orgMuseum in Newark, Ohio, run by Heisey Collectors of America, with exhibits including Heisey reissues and look-alikes.Unchanged
National Imperial Glass Collectors' Society / National Imperial Glass MuseumMuseumimperialglass.org/museumCollectors society that studies the Imperial Glass Company of Bellaire, Ohio, and maintains a museum of Imperial glass and artifacts.http://www.imperialglass.org/site/museum.htm
Ohio Glass Museum & Glass Blowing StudioMuseumohioglassmuseum.orgMuseum and glassblowing studio at 124 W. Main Street, Lancaster, Ohio, covering the history and industry of glassmaking.https://ohioglassmuseum.org/index.php
Sandwich Glass Museum (Sandwich Historical Society)Museumsandwichglassmuseum.orgMuseum in Sandwich, Massachusetts, run by the Sandwich Historical Society, interpreting the town history and its glass industry, with hourly glassmaking presentations.http://www.sandwichglassmusuem.org/
Shanghai Museum of GlassMuseumshmog.orgMuseum opened in 2011 on the former Shanghai No. 1 Glass Factory site in Baoshan, Shanghai, showing contemporary glass art and design.http://en.shmog.org/index.php
Suomen Lasimuseo (Finnish Glass Museum)Museumsuomenlasimuseo.fi/englishNational museum of glass design and glass history in a renovated glassworks at Tehtaankatu 23, Riihimäki, Finland.http://www.suomenlasimuseo.fi/Suomen-Lasimuseo/Finnish-Glass-Museum/
Sveriges glasmuseum (Swedish Glass Museum), Kulturparken SmålandMuseumkulturparkensmaland.se/sverigesglasmuseumThe Swedish Glass Museum in Växjö, in the same building as the Småland Museum, showing Swedish glass from the earliest times to modern studio glass.http://www.kulturparkensmaland.se/1.0.1.0/31/2/
Tiffin Glass Museum and ShoppeMuseumtiffinglass.orgMuseum of Tiffin glass at 27 S Washington St., Tiffin, Ohio.Unchanged
Carder Steuben Glass Association (formerly Carder Steuben Club)Clubsteubenglass.orgCollectors association in Corning, New York, promoting the collecting of Carder-era and later Steuben glass; publishes the Gazelle Gazette and hosts the Shape Gallery database and annual symposium.http://www.cardersteubenclub.com/http://www.cardersteubenclub.com
Early American Pattern Glass SocietyClubeapgs.orgCollectors society for early American pattern glass that runs a large pattern ID database.Unchanged
Federation of Historical Bottle Collectors (FOHBC)Clubfohbc.orgNational federation founded in 1969 for antique bottle and glass collectors; publishes Antique Bottle & Glass Collector magazine and runs a virtual museum.https://www.fohbc.org/bottles-extras/
Heart of America Carnival Glass AssociationClubhoacga.comCarnival glass collectors association; 2026 convention held jointly with the International Carnival Glass Association.Unchanged
National Fenton Glass SocietyClubnfgs.orgNonprofit society chartered in Ohio in 1990 to promote the study of handmade glass, especially Fenton Art Glass, based at 156 Front St., Marietta, Ohio.http://www.fentonglasssociety.org/
The Glass Society (successor of The Glass Association, UK)Clubtheglasssociety.orgInternational society of collectors and enthusiasts of historical and contemporary glass, formed in 2019 by merging The Glass Circle and The Glass Association.http://www.glassassociation.org.ukhttp://www.glassassociation.org.uk/
The Stretch Glass SocietyClubstretchglasssociety.orgCollectors society for iridescent American stretch glass; publishes the Quarterly and hosts Stretch-Out discussions.Unchanged
BLM/SHA Historic Glass Bottle Identification & Information WebsiteReferencesecure-sha.org/bottleReference site for dating and typing utilitarian bottles and jars made in the United States and Canada from the late 1700s to the 1950s, hosted by the Society for Historical Archaeology.Unchanged
Glass Bottle Marks (David Whitten)Referenceglassbottlemarks.comReference site on manufacturers' marks on bottles, insulators and tableware made in the United States.Unchanged
Glass Museum On Line (Angela Bowey)Referencetheglassmuseum.comOnline glass museum of in-depth articles on a wide range of glass, edited by Angela Bowey; the old glass.co.nz address now redirects here.http://www.glass.co.nzhttp://www.glass.co.nz/
The Glass Encyclopedia (Angela Bowey)Referenceglassencyclopedia.comReference site with one page per glass topic or maker, giving a definition, background and history, pictures, and suggested books.http://www.glassencyclopedia.comhttp://www.glassencyclopedia.com/Dartingtonglass.htmlhttp://www.glassencyclopedia.com/Frankthrowerglass.html
2-Clicks Antique Glassware (Antique Glass Guide)ReferenceNo successor foundArchived copyAntique glass guide and directory organized by type, period and country.http://www.2-clicks-antiqueglassware.com
Blenko Museum (independent, founded by Bill Agle)MuseumNo successor foundArchived copyIndependent museum founded in 2000 that held survey exhibitions of Blenko Glass Company work; its physical space closed in 2004.http://http://www.blenkomuseum.org/
Caithness Glass Collectors CircleClubNo successor foundArchived copyFormer collectors club page on the Caithness Glass company site.https://www.caithnessglass.co.uk/collectors-circle
Carnival Glass Collectors Association of Australia (page on Carnival Glass Worldwide)ClubNo successor foundPage about the Australian carnival glass collectors association on the Thistlewoods' Carnival Glass Worldwide site; the page now returns 404.http://www.carnivalglassworldwide.com/cgcaa.html
Contemporary Carnival Glass (carnivalglass.net)ReferenceNo successor foundArchived copyCollector site with company histories and articles on carnival glass made from the 1950s to the 1990s.http://www.carnivalglass.net/
Dave & Renee's Stretch Glass Site (shetlarglass.com)ReferenceNo successor foundArchived copyCollectors' photo site on iridescent American stretch glass.http://www.shetlarglass.com/stretchglass/SGopenpage.htm
DelMarVa Depression Glass Club (Maryland)ClubNo successor foundArchived copyMaryland collectors club for Depression-era American glassware that hosted glass shows.https://www.delmarvaglassclub.org/
Fenton Art Glass: Collector Clubs pageReferenceNo successor foundArchived copyFenton company page listing independent Fenton collector clubs; removed from the current Fenton site.http://www.fentonartglass.com/clubs/
Glass Collectors' Society Inc. (South Australia)ClubNo successor foundArchived copySouth Australian glassware collectors club, now wound up.http://www.glasscollectorssociety.org.au/
Glass Fire Grenades (glassfiregrenades.com)ReferenceNo successor foundArchived copyCollector information site on glass fire extinguishers (Red Comet, Shur-Stop, Autofyrstop and others).http://www.glassfiregrenades.com/
Glass Target Balls (glasstargetballs.com)ReferenceNo successor foundArchived copyCollector reference on glass target balls by country, with related firearms and shooting history.http://www.glasstargetballs.com/http://www.glasstargetballs.com/index.php?option=com_frontpage&Itemid=1
Glass of the British Military ca. 1755-1820 (Parks Canada, hosted by SHA)ReferenceNo successor foundArchived copyParks Canada study by Olive R. Jones and E. Ann Smith on glass used by the British military, ca. 1755-1820, formerly hosted as a PDF by the Society for Historical Archaeology.https://sha.org/assets/documents/Glass%20of%20the%20British%20Military%20-%20English.pdf
Glass411 (character and advertising glass database)ReferenceNo successor foundArchived copyOnline database of cartoon, character and advertising drinking glasses.http://www.glass411.info/https://www.glass411.info/
Glassmaking in London (David Watts)ReferenceNo successor foundArchived copyReference site on the history of London glasshouses, archaeology, industries and studio glass.http://www.glassmaking-in-london.co.uk/
Goofus Glass Museum and Information Center (G. David Ballentine)ReferenceNo successor foundArchived copyOnline goofus glass museum and information center by G. David Ballentine, with a collectors forum.http://www.goofus.org/index.htmlhttp://www.goofus.org/
Minnesota Museum of American Pattern GlassMuseumNo successor foundArchived copyMinneapolis museum of American pressed pattern glass; its own site later announced it had permanently closed.http://www.mnmapg.org/
Mt. Washington & Pairpoint Glass SocietyClubNo successor foundArchived copyCollectors society for Mt. Washington and Pairpoint glass, with image galleries of Burmese, Crown Milano, Royal Flemish and other lines.http://www.mwpgs.net/
Pattern Glass School (PatternGlass.com)ReferenceNo successor foundArchived copyOnline lessons on Early American Pattern Glass from PatternGlass.com.http://www.patternglass.com/lc.homepage.htm
The Shot Glass Database (pre-pro.com)ReferenceNo successor foundArchived copyAlphabetical index of individual shot glass listings on pre-pro.com.http://www.pre-pro.com/midacore/index.php
West Michigan Glass ClubClubNo successor foundArchived copyGrand Rapids, Michigan, collectors club whose members collected pattern glass, paperweights and art glass.http://www.netnz.com/Michigan/

For librarians, teachers and collector clubs

This guide is licensed CC BY 4.0. Link to it, print the cheat sheet, put it in a research guide, a club newsletter or a class packet; just credit The Mark Index. There are no ads and nothing to sign up for. Club newsletter editors are welcome to reprint the maker table with credit. Found an error or a better source? Tell us.

Chicago
The Mark Index Editors. “Glass Makers’ Marks: Identify and Date American Pressed, Depression and Art Glass.” The Mark Index. Last modified October 6, 2026. https://themarkindex.com/glass-makers-marks/.
MLA
“Glass Makers’ Marks: Identify and Date American Pressed, Depression and Art Glass.” The Mark Index, 6 Oct. 2026, themarkindex.com/glass-makers-marks/.
APA
The Mark Index Editors. (2026, October 6). Glass makers’ marks: Identify and date American pressed, Depression and art glass. The Mark Index. https://themarkindex.com/glass-makers-marks/
Link HTML
<a href="https://themarkindex.com/glass-makers-marks/">Glass Makers' Marks: Identify and Date American Pressed, Depression and Art Glass</a> (The Mark Index, CC BY 4.0)

How we built this guide

We read collector-society research (the National Depression Glass Association, Heisey Collectors of America, the National Imperial Glass Collectors’ Society, National Cambridge Collectors, the Early American Pattern Glass Society, the Stretch Glass Society, the Carnival Glass Society and others), the Bottle Research Group’s chapters on tableware makers, David Whitten’s Glass Bottle Marks, museum pages, and USPTO trademark records. We opened every source on October 6, 2026 and kept the quotation that supports each date.

Our rule is two independent sources for every date. Of 78 marks, 39 have two or more; the other 39 carry a “one source” flag and stay out of the tool and the cheat sheet. Several collector pages draw on the same older books (Toulouse, Peterson), so we note where independence is partial. Steuben marks are all single-source for now because the Corning Museum of Glass’s object records were not reachable for checking. We found no source for a Duncan & Miller mark. We don’t put values on anything.

The directory was link-checked on October 6, 2026: 27 addresses answered, and 20 old resources are gone, listed with an archived copy where one exists.

Sources

  1. SecondaryThe Henry Ford. "Pressed Glass" (expert set), Digital Collections, The Henry Ford, Dearborn, Michigan, accessed 2026-10-06.. thehenryford.org
  2. SecondaryVictoria and Albert Museum. Celery-jar, press-moulded glass, 'Chandelier' pattern, O'Hara Glass, Pittsburgh, ca. 1890 (object O1254479), catalog summary, accessed 2026-10-06.. collections.vam.ac.uk
  3. SecondaryGeorge, Sean, and Wendy Jones. "A Brief History of Antique Pressed Glass." Early American Pattern Glass Society website (reprinted with permission of Sean George Pressed Glass & Goblets), accessed 2026-10-06.. eapgs.org
  4. SecondaryCotter (NDGA). "What is Depression Glass? For That Matter, What is Elegant Glass?." National Depression Glass Association website (ndga.net), accessed 2026-10-06.. ndga.net
  5. SecondaryWhite, Carole Bess, and Dennis Headrick. "Glass Factories On Postcards." Webfooters Post Card Club, 2009; PDF hosted by the Early American Pattern Glass Society, accessed 2026-10-06.. eapgs.org
  6. SecondaryRichards, Dave, Trudy Auty, and Steve Auty (Carnival Glass Society Research Team). "Carnival Glass – A Concise Guide," section 2. The Carnival Glass Society (UK), 2019, accessed 2026-10-06.. thecgs.co.uk
  7. SecondaryRichards, Dave, Trudy Auty, and Steve Auty (Carnival Glass Society Research Team). "Carnival Glass – A Concise Guide," section 4. The Carnival Glass Society (UK), 2019, accessed 2026-10-06.. thecgs.co.uk
  8. SecondaryDoty (NDGA). "A Brief History of Carnival Glass." National Depression Glass Association website (ndga.net), accessed 2026-10-06.. ndga.net
  9. SecondaryStretch Glass Society. Home page ("Stretch Glass: What Is It?" and mission statement), accessed 2026-10-06.. stretchglasssociety.org
  10. SecondaryJones (NDGA, 2008). "Stretch Glass." National Depression Glass Association website (ndga.net), accessed 2026-10-06.. ndga.net
  11. SecondaryNDGA (2012). "Stretch Glass." National Depression Glass Association website (ndga.net), accessed 2026-10-06.. ndga.net
  12. SecondaryNational Depression Glass Association. Home page, accessed 2026-10-06.. ndga.net
  13. SecondaryNDGA. "What is Depression Glass." National Depression Glass Association website (ndga.net), accessed 2026-10-06.. ndga.net
  14. SecondaryEick (NDGA). "Etched Depression Glass vs. Depression Glass vs Elegant." National Depression Glass Association website (ndga.net), accessed 2026-10-06.. ndga.net
  15. SecondaryThe Wolfsonian-FIU. "Color and Form: American Depression Glass" (exhibition page, opened December 2020), accessed 2026-10-06.. wolfsonian.org
  16. SecondaryCollege of Charleston Arts and Cultural Heritage (aah) blog. "Storeroom Stories: More Than Just a Collectible" (on a Charleston Museum Depression glass pitcher), 2015, accessed 2026-10-06.. blogs.charleston.edu
  17. SecondaryOak Ridge Associated Universities, Museum of Radiation and Radioactivity (Health Physics Historical Instrumentation Museum Collection). "Vaseline and Uranium Glass (ca. 1930s)," accessed 2026-10-06.. orau.org
  18. SecondaryMichigan State University Campus Archaeology Program. "Gunson's Glowing Glass: History and Archaeology of Uranium Glass" (updated 12/16/2022), accessed 2026-10-06.. campusarch.msu.edu
  19. SecondaryOak Ridge Associated Universities. "A glowing review of uranium glass," ORAU museum blog, accessed 2026-10-06.. orau.org
  20. PrimaryHeisey Glass Museum (Heisey Collectors of America). "The Heisey Story.". heiseymuseum.org
  21. PrimaryHeisey Glass Museum. "Learn About Heisey Glass" (FAQ).. heiseymuseum.org
  22. SecondaryBirckbichler, Lamar. "Unmarked Heisey?" Glass and More (May 1998), reprinted by National Depression Glass Association.. ndga.net
  23. SecondaryBowey, Angela M. "Heisey Glass." Glass Encyclopedia.. glassencyclopedia.com
  24. SecondaryWhitten, David. "Glass Bottle Marks" alphabetical list, page 3 (E-L).. glassbottlemarks.com
  25. PrimaryHeisey Glass Museum. "Heisey's Glass Menagerie.". heiseymuseum.org
  26. PrimaryHeisey Glass Museum. "Exhibits" (Reproductions and Look-Alikes).. heiseymuseum.org
  27. SecondaryWhitten, David. "Glass Bottle Marks" "Fenton Art Glass Company".. glassbottlemarks.com
  28. SecondaryNagy (NDGA). "Fenton Crest" article, National Depression Glass Association.. ndga.net
  29. SecondaryBowey, Angela M. "Fenton Art Glass." Glass Encyclopedia.. glassencyclopedia.com
  30. SecondaryNational Depression Glass Association. "Fenton auction" notice and company timeline.. ndga.net
  31. PrimaryFenton Art Glass Company. "The Fenton Logo in our Glass … A Bit of History" (reprinted with permission by National Depression Glass Association).. ndga.net
  32. SecondaryWhitten, David. "Glass Bottle Marks" alphabetical list, page 4 (M-R).. glassbottlemarks.com
  33. SecondaryThistlewood, Glen and Stephen. "Trademarks and Makers Marks on Classic Carnival around the World." Carnival Glass Worldwide.. carnivalglassworldwide.com
  34. Secondarye-WV: The West Virginia Encyclopedia. "Fenton Art Glass Company.". wvencyclopedia.org
  35. PrimaryNational Imperial Glass Collectors' Society. "History.". imperialglass.org
  36. SecondaryBowey, Angela M. "Imperial Glass." Glass Encyclopedia.. glassencyclopedia.com
  37. SecondaryThistlewood, Glen and Stephen. "Imperial Revival Carnival Glass." Carnival Glass Worldwide.. carnivalglassworldwide.com
  38. PrimaryNational Westmoreland Glass Collectors' Club. "History" (Key Moments in Westmoreland History).. westmorelandglassclub.org
  39. SecondaryWhitten, David. "Glass Bottle Marks" alphabetical list, page 5 (S-Z).. glassbottlemarks.com
  40. SecondaryBowey, Angela M. "Westmoreland Glass." Glass Encyclopedia.. glassencyclopedia.com
  41. SecondaryNagy (NDGA). Westmoreland article (part 3), National Depression Glass Association.. ndga.net
  42. PrimaryNational Westmoreland Glass Collectors' Club. "Trademarks and Labels.". westmorelandglassclub.org
  43. PrimaryNye, Mark. "Trademarks – Part I." The Crystal Ball no. 375 (July 2004), National Cambridge Collectors.. cambridgeglass.org
  44. Primary"'NEARCUT' – The Final Years of a Great Era." The Crystal Ball (July 1987), National Cambridge Collectors.. cambridgeglass.org
  45. SecondaryWhitten, David. "Glass Bottle Marks" alphabetical list, page 2 (C-D).. glassbottlemarks.com
  46. Primary"About the Trademark." The Crystal Ball no. 293 (September 1997), National Cambridge Collectors.. cambridgeglass.org
  47. PrimaryNational Cambridge Collectors. "History.". cambridgeglass.org
  48. SecondaryLockhart, Bill, Beau Schriever, Bill Lindsey, and Carol Serr. "Other N Marks." Bottle Research Group / Society for Historical Archaeology.. secure-sha.org
  49. SecondaryBowey, Angela M. "Northwood Glass." Glass Encyclopedia.. glassencyclopedia.com
  50. PrimaryUSPTO TSDR, reg. no. 376,781 (anchor-H). tsdr.uspto.gov
  51. SecondaryLockhart et al., "Anchor Hocking Glass Corp.", Encyclopedia of Manufacturers' Marks. secure-sha.org
  52. SecondaryWhitten, "Anchor Hocking Glass Corporation". glassbottlemarks.com
  53. PrimaryUSPTO TSDR, reg. no. 5,607,824 (redrawn anchor-H). tsdr.uspto.gov
  54. PrimaryUSPTO TSDR, reg. no. 388,452 (FIRE-KING). tsdr.uspto.gov
  55. SecondaryCorning Museum of Glass, Rakow Research Library, "Ask a Glass Question" FAQ 143773. libanswers.cmog.org
  56. PrimaryUSPTO TSDR, reg. no. 1,122,404 (boxed anchor). tsdr.uspto.gov
  57. PrimaryUSPTO TSDR, reg. no. 3,817,905 (plain anchor). tsdr.uspto.gov
  58. SecondaryLockhart et al., "Hazel-Atlas Glass Co.". secure-sha.org
  59. SecondaryWhitten, "Hazel-Atlas Glass Company". glassbottlemarks.com
  60. SecondaryLockhart et al., "Federal Glass Co.". secure-sha.org
  61. SecondaryWhitten, "Federal Glass Company, Columbus, Ohio". glassbottlemarks.com
  62. SecondaryKathy Eickholt, "Federal Glass Patterns After the Depression". ndga.net
  63. SecondaryLockhart, Schriever, Lindsey and Serr, "Jeannette Glass Co.". secure-sha.org
  64. SecondaryKathy Eickholt, "Jeannette Glass Company's post-Depression patterns". ndga.net
  65. Secondary"Boyd Glass", Glass Encyclopedia. glassencyclopedia.com
  66. SecondaryWhitten, "Boyd's Crystal Art Glass: B in a diamond mark on glassware". glassbottlemarks.com
  67. Secondary"Degenhart Owl History", Degenhart Owl Depot. degenhartowldepot.com
  68. Secondary"Identify Age & Maker's Marks", Degenhart Owl Depot. degenhartowldepot.com
  69. PrimaryUSPTO TSDR, reg. no. 115,846 (PYREX). tsdr.uspto.gov
  70. SecondaryWhitten, "Pyrex Glass – Basic Info". glassbottlemarks.com
  71. Secondary"Pyrex Flameware". ndga.net
  72. Secondary"Blenko marks". blenkocollectors.com
  73. Secondary"Blendo Blenko". atomic-ranch.com
  74. Secondary"John W. Blenko's Sandblasted Signature" (product page). blenko.com
  75. SecondaryWhitten, Glass Bottle Marks page 1 (Blenko Handcraft entry). glassbottlemarks.com
  76. Secondary"Blenko Glass", e-WV: The West Virginia Encyclopedia. wvencyclopedia.org
  77. Secondary"Summit Art Glass Company – Akron, Ohio". carnivalglassclubs.com
  78. SecondaryNational Westmoreland Glass Collectors' Club. "Fostoria Early Opal Decorated Vases" (collection entry).. westmorelandglassclub.org
  79. PrimaryFostoria Glass Society of America / Fostoria Glass Museum. "History of the Fostoria Glass Company 1887-1986.". fostoriaglass.org
  80. Secondarye-WV: The West Virginia Encyclopedia. "Fostoria Glass.". wvencyclopedia.org
  81. SecondaryBowey, Angela M. "Fostoria Glass." Glass Encyclopedia.. glassencyclopedia.com
  82. Secondary"A Salute to Dugan – Diamond." The Carnival Pump vol. XX no. 12 (December 1989), International Carnival Glass Association.. internationalcarnivalglass.com
  83. SecondaryThistlewood, Glen and Stephen. "Dugan-Diamond (Indiana, Pennsylvania)." Carnival Glass Worldwide.. carnivalglassworldwide.com
  84. PrimaryTiffin Glass Museum. "The History of Tiffin Glass" (history courtesy of Goshe, Hemminger and Pina, '40s, '50s & '60s Stemware by Tiffin).. tiffinglass.org
  85. SecondaryBowey, Angela M. "Tiffin Glass." Glass Encyclopedia.. glassencyclopedia.com
  86. Secondary"Duncan Glass made at Tiffin, OH." Rainbow Reports (1985), National Depression Glass Association.. ndga.net
  87. Secondary"Duncan & Miller's 'Canterbury' Pattern." Rainbow Reports (1976), National Depression Glass Association.. ndga.net
  88. SecondaryWikipedia. "Duncan & Miller Glass Company.". en.wikipedia.org
  89. PrimaryNational Duncan Glass Society. "A History in Color.". duncan-miller.org
  90. Secondary"Is that Opalescent piece really Duncan?" Rainbow Reports (1975), National Depression Glass Association.. ndga.net
  91. SecondaryWhitten, "Indiana Glass Company Hen-on-Nest Dishes". glassbottlemarks.com
  92. SecondaryKathy Eickholt, "Indiana Glass Later Patterns". ndga.net
  93. SecondaryLockhart and Bernas, "The Anchor Glass Co., L.E. Smith Glass Co., and the Mystery of the Anchor Fruit Jar". secure-sha.org
  94. SecondaryFrank O. Swanson, "One Hundred Years in Toledo 1888-1988". cutglass.org
  95. Secondary"Our Story", Libbey Inc.. libbey.com
  96. SecondaryWhitten, "Letter L in cursive script mark: Libbey Glass Company". glassbottlemarks.com
  97. Secondary"Steuben Signatures and Forgeries". steubenglass.org
  98. Secondary"A History Refresher", Gazelle Gazette. steubenglass.org
  99. Secondary"What's This About the Letter S?", Gazelle Gazette. steubenglass.org
  100. Secondary"Steuben Glass" (Collectors Weekly text). ndga.net
  101. Secondary"The Mosser Family". mosserglass.com
  102. SecondaryWhitten, "Robin in Tree child's mug". glassbottlemarks.com
  103. SecondaryNagy (NDGA). "A Depression Glass Primer." National Depression Glass Association website (ndga.net), accessed 2026-10-06.. ndga.net

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