Patent numbers and ‘Pat. Pend.’ as dating tools
A patent number converts to the year it issued. Tables of first design and utility numbers, plus why that year is the earliest date, not the date made.
Quick answerA US patent number can be converted to the year the patent issued with a table of patent numbers by year, which lists the first number granted each year. Check whether it’s a design patent (numbers start with D and run much lower) or a utility patent before you look it up. The result dates the patent, not your piece: production often ran for years or decades after, and “Pat. Pend.” only means an application was said to be filed.
Patent marks turn up on costume jewelry and stoneware alike, and they’re among the few marks that point to a specific year. This guide shows how to turn a number into an issue year, how to read “Pat. Pend.” and similar wording, and why the year you find is an earliest date rather than a date of manufacture. It can’t tell you how long a design stayed in production; only the maker’s history can do that.
Utility patent or design patent?
The US runs two separate numbering sequences, and mixing them up is an easy lookup error to make. Utility patents have been numbered since 1836. Design patents began in 1842, and they’re the kind the costume jewelry firms relied on.
Design numbers carry a D prefix and run far lower than utility numbers from the same years. A number like D130,000 and a number like 2,300,000 can come from the same period. If you look up a design number in the utility table, you’ll land before 1900, decades too early.
Between 1861 and 1981, design patents ran for terms of 3.5, 7 or 14 years. CJCI reports that for the costume jewelry makers, design patents lasted only 3.5 to 7 years.
Converting a number to a year
The USPTO publishes a report called “Issue Years and Patent Numbers” that lists the first utility, design, plant and reissue patent numbers issued in each year. The tables below come from a library guide, the Queen’s University Engineering and Science Library’s U.S. Patent Number Guide, which reproduces those USPTO tables. We give only the years it lists.
First utility patent number issued in selected years
| Year | First utility number |
|---|---|
| 1900 | 640,167 |
| 1910 | 945,010 |
| 1920 | 1,326,899 |
| 1930 | 1,742,181 |
| 1940 | 2,185,170 |
| 1950 | 2,492,944 |
| 1955 | 2,698,434 |
| 1960 | 2,919,443 |
| 1970 | 3,487,470 |
| 1980 | 4,180,867 |
First design patent number issued in selected years
| Year | First design number |
|---|---|
| 1935 | D94,179 |
| 1937 | D102,601 |
| 1939 | D112,765 |
| 1941 | D124,503 |
| 1942 | D130,989 |
| 1945 | D139,862 |
| 1950 | D156,686 |
| 1955 | D173,777 |
| 1960 | D186,973 |
| 1965 | D199,955 |
The 1940 figure didn’t come through in the table we worked from, so the design list jumps from 1939 to 1941. We couldn’t open the USPTO’s own report page, so treat these as a guide and confirm any single patent by pulling up the patent document itself on a patent search site such as Google Patents.
To use the tables:
- Copy the number exactly, including any D prefix.
- Pick the matching table: design numbers go to the design table, plain numbers to the utility table.
- Find the two listed years your number falls between. Suppose a brooch reads D140,000: that’s above D139,862 (1945) and below D156,686 (1950), so the patent issued between 1945 and 1949.
- Because the tables list only some years, you’ll often get a span. Look up the patent document to get the exact issue date.
- Treat the result as the earliest date for the design. Your piece could have been made that year or long after.
What the patent document gives you
Once you’ve found the patent itself, it tells you more than the table can. Patent documents include illustrations of the design along with the filing and issue dates. The drawing lets you check that your piece matches the patented design, and the filing date shows when the maker first applied.
“Pat. Pend.” and “Patent Applied For”
These phrases mean the maker said an application had been filed. They don’t mean a patent was ever granted, so a “Pat. Pend.” piece may have no patent document to find.
That said, “applied for” wording can mark a narrow window when a maker’s history is well documented. The Red Wing Collectors Society reports that only Red Wing jars stamped “Patent Applied For” date closely, to August through December 1915.
Why a patent date isn’t a production date
Makers kept stamping patent numbers and dates long after the grant. Red Wing again gives the clearest example: it stamped a December 1915 handle patent on every handled jar it made through 1947, more than 30 years later. A jar showing that 1915 date could have been made in any of those years.
So read every patent mark as “no earlier than”. A tight window like the Red Wing “Patent Applied For” jars is unusual.
Patents on costume jewelry
Costume jewelry companies began patenting their designs in the late 1930s. Costume Jewelry Collectors International (CJCI) reports that Trifari and Coro filed the most, and that Marcel Boucher held about 95 patents. After 1955, most jewelry makers switched from patents to copyright, so patent marks are chiefly a tool for pieces from the late 1930s to the mid-1950s. Coro was the exception: CJCI reports it kept patenting until 1965.
CJCI notes that some period copies bore “PAT PEND” in raised letters rather than incised ones. That’s a sign the piece was cast from a mold taken off an original. If the patent wording on your piece stands up from the surface instead of being cut into it, give the piece a hard second look.
Putting it together
Read the full mark, sort design from utility, and convert the number with the tables above. Then pull the patent document to confirm the drawing and the exact dates, and treat what you find as the earliest the design could be. For jewelry made after the mid-1950s, the copyright symbol is the more useful clue; see what the copyright symbol on costume jewelry tells you.
Maker entries show how each firm’s marks changed: try Trifari, Marcel Boucher or, for stoneware, Red Wing Union Stoneware. If you only have part of a mark, start with the Mark Finder.
Sources
- U.S. Patent Number Guide – Queen’s University Engineering and Science Library (compiled from USPTO “Issue Years and Patent Numbers”)
- USPTO Issue Years and Patent Numbers report
- Foiling the Style Pirates: Costume Jewelry Exclusives, Patents and Copyrights (Robin Deutsch) – Costume Jewelry Collectors Int’l
- Vintage Costume Jewelry Tools for Dating – Costume Jewelry Collectors Int’l
- The Red Wing Union Stoneware Company – Red Wing Collectors Society
Questions people ask
When did US design patents start?
US design patents began in 1842. Utility patents were numbered from 1836.
How long did a design patent last?
Between 1861 and 1981, design patent terms were 3.5, 7 or 14 years. CJCI reports that for costume jewelry makers, design patents lasted only 3.5 to 7 years.
Which costume jewelry makers held the most patents?
Costume Jewelry Collectors International reports that Trifari and Coro filed the most, and that Marcel Boucher held about 95 patents. Companies began patenting designs in the late 1930s.
Where do the patent number tables come from?
The USPTO publishes an 'Issue Years and Patent Numbers' report listing the first patent numbers issued each year. Our tables come from a Queen's University library guide that reproduces those USPTO figures.
The Mark Index is a reference for identifying and dating marks. It isn’t an appraisal or a guarantee of authenticity. Reproductions and later reissues can carry old marks.