So, is there anything better than flipping over some old jewelry and seeing "Pat. Pend" written on the back? I love that feeling. It feels like a whisper from the past. But I’ve noticed a lot of people get confused about this. "Patent Pending" is just a status—it’s not a guarantee that you struck gold, and it’s not a date. It just means "I made this, and the government is checking it."
Honestly, trying to date vintage jewelry just by how it looks is a total guessing game. Trends are messy. But patent numbers are solid proof. I wrote this to help you guys stop guessing and actually figure out how to look this stuff up. It’s basically the closest thing we have to time travel.
WHAT “PAT. PEND” REALLY MEANS IN MID-CENTURY COSTUME JEWELRY
When you see "Pat. Pend" stamped into the pot metal of a 1950s necklace, it signifies a specific legal limbo. It means the manufacturer had submitted an application to the United States Patent Office but had not yet been granted the final patent number. This distinction is crucial because it creates a specific timeframe for the piece.
The Window of Production.
A "Patent Pending" mark typically indicates early production runs. Once the patent was granted, reputable manufacturers usually updated their molds to display the actual patent number (e.g., "Pat. 2,123,456"). Therefore, finding a piece with "Pat. Pend" suggests it was likely manufactured during that interim period between application and approval, which could range from a few months to a couple of years.
The Mark of Ambition.
Beyond the timeline, this mark tells you something about the manufacturer's intent. Applying for a patent was expensive and time-consuming. Cheap, fly-by-night companies rarely bothered. Seeing "Pat. Pend" usually indicates a company that valued its intellectual property and invested in original designs—think Trifari, Coro, or Boucher—rather than a company that simply copied existing trends.
WHY PATENT NUMBERS ARE MORE RELIABLE THAN STYLE ALONE FOR DATING JEWELRY
I often hear new collectors say, "That looks like an Art Deco piece, so it must be from the 1920s." This is a dangerous assumption. The 1920s style saw massive revivals in the 1950s and again in the 1970s. Relying purely on visual cues is subjective and prone to error.
The Objective Timeline.
Patent numbers provide hard data. If a brooch is stamped with a Design Patent number granted in 1951, that piece physically cannot have been made in 1940, no matter how much it looks like a pre-war design. It sets a hard "earliest possible date" (the terminus post quem), which is the bedrock of accurate dating.
Tracing the Designer’s Hand.
Style analysis often fails to account for individual designer idiosyncrasies. Alfred Philippe, the legendary designer for Trifari, brought fine jewelry techniques to costume pieces.2 His designs often looked far more expensive and "classic" than their contemporaries. A style analysis might misdate his work because it transcends the kitsch of the era, but his patent numbers place him precisely in history.
HOW THE U.S. PATENT SYSTEM WORKED FOR JEWELRY DESIGNERS (1940S–1960S)
To use these numbers, you have to understand the machine that generated them. The mid-century era was the golden age of costume jewelry patents. The market was fiercely competitive, and copying was rampant.
The Application Process.
A designer would sketch a piece—a floral spray, a stylized animal, a geometric link—and submit detailed drawings to the patent office. These drawings are works of art in themselves. If you look up patents from this era, you will often see the name of the assignee (the company, like Coro, Inc.) and the inventor (the designer, like Adolph Katz).
The Public Record.
Once granted, these patents became public record. This transparency is what saves us today. While company records were often thrown out when factories closed or were bought out, the U.S. government kept everything. We have a continuous, unbroken record of American jewelry design innovation that serves as our primary reference library today.
PATENT APPLICATION DATE VS. GRANT DATE: WHICH ONE MATTERS FOR DATING JEWELRY?
This is where many resellers get tripped up. A patent document lists two dates: the date filed and the date patented.
The Date Filed.
This is when the design was submitted. It represents the moment of creation. If a patent was filed in late 1949 but granted in 1951, the design is effectively a 1949 concept. However, production likely started shortly after filing, while the "Pat. Pend" mark was used.
The Date Patented.
This is when the legal protection officially started. Manufacturers would switch their stamps to the patent number after this date. When dating a piece with a patent number, the grant date tells you the earliest the piece could have been stamped with that number. It could have been made five years later, but it couldn't have been made before.
STEP-BY-STEP GUIDE: USING PATENT NUMBERS TO ACCURATELY DATE COSTUME JEWELRY
Finding the number is only the first step. Here is how I process a piece when I’m sitting at my desk with a loupe and a laptop.
Step 1: Locate and Clean the Mark.
Use a 10x jeweler’s loupe. Patent numbers are often hidden in obscure places—on the back of a pin mechanism, on the clasp of a necklace, or on the edge of a link. They can be incredibly small. If the area is grimy, use a soft toothbrush and a little water to clear the debris. Do not scrape it; you might damage the plating.
Step 2: Identify the Sequence.
Determine if you are looking at a Design Patent (usually starts with a "D" followed by numbers, e.g., Des. 150,000) or a Utility Patent (just a string of numbers, usually longer, e.g., 2,500,000). This distinction dictates which database or chart you need to consult.
Step 3: Consult the Reference Tables.
You don't need to search the patent office for every single item if you have a reference table. You check where your number falls within the year ranges. If your number is higher than the first patent of 1955 but lower than the first patent of 1956, your design was patented in 1955.
COMMON JEWELRY PATENT PREFIXES AND WHAT THEY REVEAL ABOUT AGE
Not all numbers are created equal. The prefix—or lack thereof—tells you what aspect of the jewelry was protected.
"Des." or "D" (Design Patents).
This protects the ornamental appearance of an object. This is the most common type for costume jewelry because the value lay in the aesthetic—the specific curve of a leaf or the arrangement of stones. These patents had shorter terms (often 3.5, 7, or 14 years), which helps narrow the dating window even further.
No Prefix (Utility Patents).
If you see a number like 2,400,000 with no letter, it is a Utility Patent. These protect functional mechanisms. In jewelry, this usually applies to earring clips, fur clips, or necklace clasps.
Elena’s Pro-Tip: A utility patent on a clasp dates the clasp, not necessarily the necklace. Manufacturers bought findings in bulk and used them for decades.
DESIGN PATENTS VS. UTILITY PATENTS IN COSTUME JEWELRY
Understanding the difference between these two is vital for accuracy. Mixing them up is the most common rookie mistake.
Table 1: Design vs. Utility Patents in Jewelry
| Feature | Design Patent | Utility Patent |
| What it Protects | The visual appearance (shape, pattern). | The mechanism (function, structure). |
| Typical Mark | "Des. Pat.", "D-", or "Pat. D-" | "Pat." followed by distinct numbers. |
| Common Uses | Brooches, specific pendant shapes. | Earring backs, pin stems, clasps. |
| Dating Value | High. Dates the specific artistic design. | Low. Dates the component, which may be reused. |
| Example | Trifari "Fruit Salad" clip design. | A specific screw-back earring mechanism. |
HOW LONG DESIGNERS USED “PAT. PEND” BEFORE UPDATING MARKS
The transition from "Pending" to a number wasn't always immediate. It depended on the factory's efficiency and the cost of re-tooling molds.
The Economic Lag.
Changing a steel mold is expensive. Even after a patent was granted, a manufacturer might continue using the "Pat. Pend" molds until they wore out or until a new production run was ordered. This creates a "bleed-over" period. A piece marked "Pat. Pend" might have been produced six months after the patent was actually granted.
The Short-Lived Designs.
Some costume jewelry was seasonal. By the time the patent was granted two years later, the style might have been out of fashion, and production ceased. In these cases, the jewelry only exists with the "Pat. Pend" mark, never the number.
FAMOUS MID-CENTURY JEWELRY BRANDS AND THEIR PATENT NUMBER PATTERNS
Different brands had different relationships with the patent office. Knowing these habits can act as a shortcut in your research.
Trifari.
Trifari was the king of patents. Under Alfred Philippe, they patented almost everything. If you find a high-quality piece that looks like Trifari but is unsigned, a patent search can often confirm it. Their patent drawings are incredibly detailed and often signed by Philippe himself.
Coro (and CoroCraft).
Coro produced massive volumes of jewelry. They patented their high-end designs (CoroCraft/Vendome) religiously. However, their lower-end lines often skipped the patent process or used generic components. Finding a patent number on a Coro piece usually elevates it to a higher collectible tier.
CASE STUDY: DATING A 1950S BROOCH USING ITS PATENT NUMBER
Let’s walk through a real-world scenario. Imagine I have found a silver-tone floral brooch. It is marked "Des. 161,123".
The Investigation.
I pull up my patent index. I see that Design Patent 161,123 was granted in late 1950.
- Step 1: The date tells me the design was released around 1950.
- Step 2: I look up the number in Google Patents. The document pops up.
- Step 3: The inventor is listed as Alfred Philippe. The assignee is Trifari, Krussman & Fishel, Inc.
- Step 4: The drawing matches my brooch perfectly.
The Conclusion.
Even if the brooch is missing the "Trifari" stamp (which happens if the plating obscures it), I have now positively identified it as a 1950 Alfred Philippe for Trifari design. The value just jumped from $20 to $150+.
WHY PATENT NUMBERS SOMETIMES APPEAR YEARS AFTER A DESIGN WAS CREATED
Sometimes the dates don't seem to make sense. You might find a piece that looks distinctly 1940s bearing a patent number from the 1950s.
The "Safe" Revival.
Companies would sometimes reissue popular designs years later. If they still held the patent, they would use the original patent number. This is why you must look at the construction of the piece—the type of clasp, the weight of the metal—alongside the patent number to determine if it’s an original issue or a later production run.
HOW WARTIME AND POST-WAR PRODUCTION DELAYS AFFECT PATENT DATING
World War II threw a wrench into the jewelry industry. Base metals were restricted for the war effort, and sterling silver became the standard substitute.
The Patent Backlog.
During the war, the patent office was overwhelmed and understaffed. Applications filed in 1942 might not have been processed until 1944 or 1945.
Material Evidence.
If you find a piece with a patent number from the war years (1941-1945) that is made of pot metal (a zinc alloy), it was likely made after the war ended and restrictions were lifted, even if the patent dates to the war. Conversely, if it is made of Sterling Silver, it was likely made during the war or immediately after.
MISTAKES COLLECTORS MAKE WHEN DATING JEWELRY BY PATENT MARKS
It is easy to get overconfident when you have a number. Here are the traps to avoid.
Assuming the Patent Date is the Production Date.
As mentioned, the patent date is the start line. A design patented in 1955 could have been produced and sold until 1965.
Confusing Findings with Designs.
Reading a patent number off an earring clip and assuming it dates the rhinestone cluster on the front is the most frequent error. The clip is just a piece of hardware; the design on the front is what matters.
Elena's Pro-Tip: Always check if the patent number is on the removable part of the jewelry. I once bought a necklace where someone had replaced the original broken clasp with a much older patented clasp. I thought I had a 1930s piece until I looked closer at the links, which were clearly 1970s revival. Trust the sum of the parts, not just the number.
WHEN A PATENT NUMBER DOESN’T MEAN AUTHENTICITY
Just because it has a number doesn't mean it's the real deal. The world of vintage jewelry is rife with "marriages" and fakes.
The Frankenstein Piece.
Repairers often swap parts. A vintage repair shop in the 1960s might have fixed a 1940s brooch using a patented pin mechanism from a different broken piece. The number belongs to the pin stem, not the brooch.
Counterfeit Stamps.
While rare in mid-tier costume jewelry, high-end pieces (like Chanel or Schiaparelli) are sometimes faked. Counterfeiters might cast a mold from an authentic piece, transferring the patent number into the fake casting. The tell-tale sign is usually a soft, mushy look to the numbers, rather than a crisp, sharp stamp.
CROSS-REFERENCING PATENT NUMBERS WITH DESIGN ARCHIVES AND CATALOGS
To get the full picture, you need to triangulate your data.
Vintage Advertisements.
Once you have a patent date (say, 1954), look for jewelry advertisements from that year. Seeing your piece in a Vogue or Harper's Bazaar ad from October 1954 confirms not just the date, but how it was marketed and what it cost originally.
Collector Books.
Reference books like Brunialti's American Costume Jewelry often list patent numbers alongside photos.3 These are invaluable for verifying that the patent number you found actually belongs to the design you are holding.
TOOLS AND DATABASES TO LOOK UP JEWELRY PATENT NUMBERS TODAY
You don't need to go to the library anymore. The tools are in your pocket.
Google Patents.
This is the gold standard. You can search by number (e.g., "US Des 150000") or by inventor name. The advanced search allows you to filter by date ranges, which is helpful if you can't quite read a digit in the stamp.
The United States Patent and Trademark Office (USPTO) Website.
While less user-friendly than Google, it is the primary source. It is useful for verifying data if Google's OCR (text recognition) has made an error.
Jewelry Patents (Website).
There are specialized databases run by collectors that curate jewelry-specific patents. These are often easier to browse because they filter out non-jewelry items.
HOW PATENT DATING IMPROVES JEWELRY VALUATION AND RESALE ACCURACY
Knowledge is profit. A dated piece is always easier to sell than an undated one.
Building Buyer Trust.
When you list an item as "Vintage Gold Tone Brooch," you are competing with thousands of listings. When you list it as "1941 Patented Trifari Fur Clip (Des. Pat. 129,xxx)," you attract serious collectors. You have done the work, and that builds trust.
Justifying the Premium.
You can explain why the price is higher. "This is an early patent pending example" is a valid selling point that justifies a premium over the later, mass-produced versions of the same design.
PATENT NUMBERS VS. COPYRIGHT MARKS: KEY DIFFERENCES COLLECTORS SHOULD KNOW
In 1955, a major legal shift occurred. A court ruling allowed jewelry designs to be copyright protected.
The Shift to ©.
After 1955, and especially into the 1960s and 70s, you see fewer patent numbers and more copyright symbols (©). Gaining a copyright was automatic and free upon publication, whereas patents were slow and costly.
The dividing Line.
If you see a © symbol, the piece is almost certainly post-1955. If you see a patent number, it is likely pre-1955 (or from a company that preferred the prestige of patents). This simple symbol is one of the quickest ways to separate mid-century from late-century vintage.
CAN PATENT NUMBERS HELP IDENTIFY UNKNOWN JEWELRY DESIGNERS?
This is my favorite part of the hunt. Many talented designers worked as "ghosts" for big firms.
Uncovering the Artist.
You might find a piece marked only with a patent number. When you look up that number, the patent document reveals the inventor's name. You might discover that a generic-looking brooch was actually designed by a famous artist who did freelance work, or by a woman designer whose name has been lost to history books but lives on in the patent record.
FINAL CHECKLIST: DATING MID-CENTURY COSTUME JEWELRY WITH CONFIDENCE
We have covered a lot of ground. Here is a quick reference guide to keep handy when you are out in the field.
Table 2: Quick Reference for Dating US Design Patents
| Patent Number Range | Approximate Year |
| D-118,000 to D-124,000 | 1940 |
| D-134,000 to D-136,000 | 1943 |
| D-143,000 to D-146,000 | 1946 |
| D-156,000 to D-161,000 | 1950 |
| D-168,000 to D-171,000 | 1953 |
| D-176,000 to D-179,000 | 1956 |
| D-187,000 to D-189,000 | 1960 |
Frequently Asked Questions About Jewelry Patents
Does "Pat. Pend" increase the value of jewelry?
Generally, yes. It indicates an early edition of the piece and suggests a higher quality of manufacturing compared to later re-issues. However, condition still reigns supreme.
Can I look up a patent if the number is worn off?
It is difficult but possible. You can search Google Patents using keywords describing the object (e.g., "brooch floral ribbon 1950") or the manufacturer's name, then visually browse the image results.
What if the patent number leads to a toaster or a car part?
You have likely misread the number or confused a Utility Patent for a Design Patent. Check the number of digits. Design patents usually have fewer digits and often start with "D".4
Did all vintage jewelry have patent numbers?
No. Many pieces were never patented, either to save money or because they were generic designs. A lack of a patent number does not mean a piece isn't vintage; it just means you have to use other dating methods.
Why do some pieces have multiple patent numbers?
This is common on complex pieces. One number might refer to the mechanism (like a clip), and another number might refer to the decorative design. Always research both.
