Gold Stamp Meanings: What 417, 1/20 12K, GF, GS, and GB Tell You About Your Find

You pull a ring out of the ground, wipe off the dirt, and find a tiny stamp inside the band. Maybe it says 417. Maybe 1/20 12K GF. Maybe 14K GS.

That stamp answers the only question that matters in the moment: is this real gold or not? You just have to know how to read it.

Nobody teaches this in one place. Purity numbers, fraction codes, and letter abbreviations come from different eras and different countries, so most people learn them one confusing find at a time. This guide puts them all together. When you finish it, you'll be able to read almost any stamp on the spot and know whether you're holding real money or pocket-spill costume jewelry.

The Two Number Systems: Karat and Fineness

Start with the basics, because every stamp builds on this.

Pure gold is 24 karat. A karat is one twenty-fourth of the total, so 14K gold is 14 parts gold and 10 parts other metals. Jewelers mix in copper, silver, zinc, and nickel to make gold harder, change its color, and lower the price. Pure gold is too soft for a ring you wear every day. It scratches and bends like lead.

Jewelry gets marked with purity in one of two ways:

• A karat stamp: 10K, 14K, 18K, 24K (sometimes 10KT or 14CT)
• A fineness number: three digits showing gold content in parts per thousand

The fineness system explains those odd numbers you find inside rings. They look random until you see the pattern:

The math is simple. Divide the karat by 24. Ten divided by 24 is 0.417, so 10K gold gets stamped 417. Fourteen divided by 24 is 0.583, stamped as 585 by convention. Once you know that, every three-digit stamp reads itself.

One rule to burn into your memory before we go further: a number only tells you the purity of the gold. The letters after the number tell you whether the piece is solid gold or just coated with it. People lose real money by reading the number and skipping the letters. The rest of this guide is mostly about those letters.

What Does 417 Mean on Gold?

A 417 stamp on gold means 10 karat solid gold. The piece is 41.7% pure gold mixed with harder metals, and it's gold all the way through, not a coating.

In the United States, 10K is the legal minimum purity that can be sold as gold under FTC jewelry guides. That's why so much American jewelry carries this mark. School class rings, military rings, fraternal rings, and plain wedding bands were made in 10K for over a century because it's tough and affordable.

Is 417 gold worth anything?

Yes, and for detectorists it's often the best stamp you can find. Three reasons:

1. It's solid. However scratched, bent, or crusty the piece is, the gold content is intact and a refiner will pay for it.
2. It survives burial well. All that alloy makes 10K harder than 14K or 18K, so a 417 ring that spent 60 years underground usually comes out looking like it was lost last summer.
3. The pieces tend to be heavy. A men's 10K class ring often weighs 8 to 15 grams. That's a serious amount of metal.

Here's how to figure the melt value of any 417 piece. Weigh it in grams, multiply by 0.417 to get pure gold content, then multiply by the current price of gold per gram (the spot price per troy ounce divided by 31.1). Look up the live spot price the day you sell, because it moves constantly.

Worked example: a 10 gram class ring holds 4.17 grams of pure gold. If gold is trading at $4,000 per troy ounce, that's about $128 per gram, so the ring carries roughly $530 in melt value. Not bad for a beep in a schoolyard.

A few marks that mean the same thing as 417: the stamp 416 (an older rounding), 10K, 10KT, and 10CT. A heart, anchor, or set of initials next to the number is the maker's trademark and doesn't change the gold content.

But if the 417 or 10K is followed by GF, GP, GE, or HGE, stop. The piece is not solid. Those letters change everything, and they're coming up next.

What Does 1/20 12K Mean?

This is the stamp that confuses more people than any other, so it's worth taking apart piece by piece.

A mark of 1/20 12K GF (sometimes just 1/20 12K) means the piece is gold-filled. Despite how "filled" sounds, there is no gold inside. It's the opposite: a sheet of real 12 karat gold has been welded with heat and pressure onto a core of brass. The fraction tells you how much. The gold layer makes up 1/20th, or 5%, of the item's total weight.

Follow the math one step further and you'll see what you're really holding. The layer is 5% of the weight, and 12K gold is only 50% pure. So the actual pure gold in a 1/20 12K piece is about 2.5% of its total weight. A 20 gram bracelet with this stamp contains around half a gram of gold.

That sounds like bad news, but gold-filled jewelry deserves respect. The bonded layer is 50 to 100 times thicker than electroplating, which is why gold-filled pieces from the 1890s still look golden today while a plated chain from the mall goes brassy in two years. From the 1880s through the 1950s, gold-filled was how ordinary Americans afforded nice things: pocket watch cases, eyeglass frames, lockets, watch chains, cufflinks. If you hunt old parks, fairgrounds, or swimming holes, you will dig gold-filled, guaranteed.

How to read any fraction stamp

The formula never changes: fraction times (karat divided by 24) equals real gold content by weight.

Two details worth remembering. US law says anything sold as gold-filled must carry at least 1/20th gold by weight. Thinner layers, like 1/40, must be called rolled gold plate instead, which is why RGP shows up on so many vintage watch cases. And no solid gold piece is ever stamped with a fraction. A fraction at the front of a stamp always means layered construction. Always.

Should you scrap 1/20 12K finds?

Not individually. A single gold-filled chain might hold a dollar or two in gold, and no refiner will weigh it out for you. Do this instead:

• Check if it's collectible first. Victorian and Art Deco gold-filled lockets, watch fobs, and bangles regularly sell to collectors for far more than melt. Identify before you scrap, every time.
• Keep a gold-filled jar. Refiners buy gold-filled by the pound in bulk lots. A coffee can that takes three seasons to fill can pay for a nice piece of gear.

The Letter Codes: GF, GP, GE, HGE, GS, GB, KP

Think of the letters as a ladder. Solid gold sits at the top, and each rung down means less gold. Here's the whole ladder in one table, then a closer look at the marks people actually search for after a confusing find.

What does 14K GS mean?

GS stands for gold shell. A layer of 14 karat gold wraps around a base metal core, the same family of construction as gold-filled. You'll see this mark most on watch cases from the 1940s through the 1960s. Elgin and Bulova stamped "10K Gold Shell" on thousands of cases, and those watches turn up in old yards and parks all the time.

A 14K GS piece is not solid gold. The 14K describes the thin shell only. Vintage gold shell watches can still be worth money to watch collectors, so don't scrap a complete watch without checking what the model sells for. As metal, treat gold shell like gold-filled: bulk lot material.

One catch to be aware of. On some costume pieces, GS was also used for "gold-plated sterling," and occasionally it's a maker's initials. If the piece carries a "sterling" or "925" mark anywhere else, the core is silver, and that changes the value in your favor.

What does 24K GB mean?

GB stands for gold bonded. A layer of gold, in this case pure 24 karat gold, is bonded over brass or copper. You'll see 24K GB on modern fashion chains, religious pendants, and jewelry from flea markets and mall kiosks.

Don't let the 24K part raise your pulse. The layer is pure gold, but it's a film over brass, and even a heavy 24K GB rope chain holds less gold than a single small solid ring. There's a useful rule hiding in this: the bigger and brighter the karat claim on cheap-feeling jewelry, the more suspicious you should be. Real solid 24K jewelry is uncommon in North America because it's too soft to wear. A huge shiny "24K" chain that feels light in the hand is telling on itself.

What does 14K FG mean?

Honest answer: FG is not a standardized code, and anyone who tells you it has one fixed meaning is guessing. On most American-made pieces, letters beside the karat mark are the maker's initials, and FG belonged to a manufacturer. On some imported pieces it's used loosely for "fine gold."

So an FG mark by itself doesn't tell you solid or plated. Work through it like this:

1. Search the rest of the piece for other letters. No GF, GP, GE, or fraction anywhere? The 14K may well be describing solid gold.
2. Look at how FG is presented. Initials inside a shield, oval, or diamond outline are a trademark, which supports the solid gold reading.
3. Test the metal. The next section covers exactly how.

When a stamp is ambiguous, the metal is the tiebreaker. Never scrap or toss a piece on an unclear stamp alone.

KP: the stamp that gets real gold thrown away

One mark deserves a public defense. 14KP does not mean 14 karat plated. The P stands for plumb, an old trade term meaning the piece is guaranteed fully 14K, from an era when marking laws let "14K" run slightly under. A KP stamp is solid gold with a quality guarantee on top. Plenty of detectorists have tossed KP rings into the junk pouch over that P. Now you won't.

How Much Gold Is Really in There?

Numbers make the ladder real. Here's what a typical 10 gram piece contains at each level, using $4,000 per troy ounce as the example price. Check the live spot price before you sell anything; the ratios below stay the same even when the price moves.

Read that table once and three things stick. The gap between solid and everything else is huge; one solid 10K ring outvalues a whole jar of gold-filled. Gold-filled is the only layered gold worth saving for its metal, and only in bulk. And plated marks have no melt value at all; whatever they're worth is in the design, the brand, or the story.

This is why learning stamps changes how you hunt. Sixty seconds with a loupe tells you whether that ring is a $500 find or a fifty-cent one, and that decides whether you grid the whole area looking for its partner or pack up and try the next site.

How to Test Gold When You Don't Trust the Stamp

Stamps wear off, get misread, and sometimes lie outright. Fake "14K" and "417" stamps on brass are common on tourist-market jewelry, and plenty of it ends up lost in parks and beaches. Test in this order, cheapest first.

1. The magnet test

Free, and it takes ten seconds. Gold is not magnetic. Neither are silver, copper, or brass, so a magnet can't prove something is gold, but it instantly exposes steel-core fakes. Carry a strong neodymium magnet in your finds pouch. If the piece jumps to it, the stamp is lying and you're done. If it doesn't react, keep going.

2. The loupe inspection

A 10x jeweler's loupe costs about ten dollars and will pay for itself the first time it saves a good find. Three things to look for:

• Wear points. Check ring shoulders, clasp edges, and anywhere the piece rubs. Plated and filled pieces show a different color metal peeking through at high spots: brassy yellow, gray, or pink. Solid gold wears down to more gold.
• The whole stamp. Worn stamps lose their letters before their numbers. What reads "14K" today may have said "14K GE" when it was new. Look for ghosts of letters after the number.
• Corrosion color. Brass and copper cores grow green crust in the ground. Solid gold comes out clean and bright after a century. The ground runs its own test on every find before you ever see it, and green crust on a "gold" ring is a verdict.

3. The density check

Gold is heavy in a way nothing else in your finds pouch is. Pure gold runs 19.3 g/cm³, 10K alloys around 11.5, brass about 8.5. With a pocket scale and a cup of water you can run a rough specific gravity test: weigh the piece dry, weigh it suspended in the water, and divide the dry weight by the difference. A big "gold" chain that comes back at brass density has answered your question.

4. The acid test

A basic acid kit costs $15 to $30 and settles most arguments. Rub the piece on the test stone, put a drop of the 10K acid on the streak, and watch. If the streak holds, step up to the 14K acid, then 18K. The streak dissolves when the acid outranks the metal. On a piece you suspect is filled or plated, file a tiny notch in a hidden spot first so the acid reaches the core instead of the coating. This is the test that separates solid 12K from 1/20 12K GF with certainty.

5. XRF for the big finds

For anything heavy, old, or potentially valuable, get an XRF scan before selling. The machine reads the exact alloy in seconds without harming the piece, and most refiners, pawn shops, and many jewelers will scan for free if you might sell. Never take the first offer on a big find without knowing exactly what it is.

One pattern makes all this testing easier: when stamps lie, they lie upward. Nobody fakes a GP stamp onto solid gold. So a stamped piece that fails physical tests is fake, full stop, while an unmarked piece that passes the magnet, loupe, and density tests deserves an acid test, because plenty of old, handmade, and worn jewelry carries no legible stamp at all.

Habits That Make Money From Dug Jewelry

Knowing the stamps is half the job. These habits are the other half.

Carry a loupe and a magnet in the field. Reading a stamp at the dig hole beats finding out three months later that the "junk" ring in your pouch was solid 417.

Log every gold-filled find location. Gold-filled concentrates where people gathered between the 1880s and 1950s: old swimming beaches, trolley parks, fairgrounds, picnic groves. One 1/20 12K watch chain out of the ground is a flag that older and better targets live in that soil, and since gold sinks deep over decades, a site shedding shallow gold-filled often holds solid gold below detection depth of an entry-level machine. Our complete metal detector guide covers which machines punch deepest on small gold.

Go easy on cleaning until you've read the stamp. Aggressive scrubbing can erase the exact mark you need, and on antique pieces the original surface is part of the value. Warm water, mild soap, soft toothbrush, and stop there until you know what you have. Our guide to cleaning finds safely covers the full process.

Sort finds into four containers, not two. Solid gold, gold-filled and shell for the bulk refining jar, sterling and vermeil, and costume. Each group has a different buyer, and mixing them costs you money at selling time.

Check your local rules before selling dug jewelry. Some states have lost property laws, and identifiable items like engraved class rings can often be traced through the school and graduation year. Returning a class ring usually earns a reward, sometimes a newspaper story, and always a landowner who invites you back. Metal detecting laws and code of ethics has the full rundown.

FAQ

What does 1/20 12K mean on jewelry?

The piece is gold-filled. A layer of real 12 karat gold is bonded onto a brass core, and that layer makes up 1/20th, or 5%, of the total weight. Since 12K gold is half pure, the piece works out to about 2.5% pure gold by weight. Not solid gold, but far more gold than any plated piece carries.

What does 417 mean on gold?

417 means 10 karat solid gold, 41.7% pure. It's the three-digit fineness version of a 10K stamp and the minimum purity that can legally be sold as gold in the US. If no letters like GF or GP follow the number, the piece is solid and has real melt value.

Is 14K GS real gold?

The outer layer is. GS means gold shell: a genuine 14 karat gold skin over a base metal core, most common on mid-century watch cases. The piece is not solid 14K, and its melt value is a small fraction of a solid piece of the same weight.

Is 24K GB worth anything?

As metal, very little. GB means gold bonded, a thin layer of 24K gold over brass or copper. Even a heavy 24K GB chain usually holds under a gram of recoverable gold. Treat a big lightweight "24K" chain as a warning sign, not a jackpot.

What does 14K FG mean?

FG is not a standard purity code. On most pieces it's a maker's initials stamped next to a real 14K mark, and on some imports it loosely means fine gold. The mark alone can't tell you if the piece is solid, so run the magnet, loupe, and acid tests before deciding.

How can I tell if a gold stamp is fake?

Test the metal against the stamp. Gold is never magnetic, never shows brass at wear points, is roughly twice as dense as brass, and holds up under the matching karat acid. A piece that fails any of those tests is fake no matter what's stamped on it. When the stamp and the metal disagree, believe the metal.

The Short Version

Three systems cover nearly every gold mark you'll meet. Numbers give purity: 417 is 10K, 585 is 14K, 750 is 18K. Fractions mean layered gold-filled construction: 1/20 12K is about 2.5% gold by weight. Letters give the construction: GF and RGP carry real gold worth saving in bulk, GS and GB are thin shells, GE, HGE, and GP are plating with no melt value, and KP is the odd one out that means fully solid. Read all three parts together, confirm with a magnet and loupe, and you'll sort any find in under a minute.

The other half of the game is digging gold in the first place, and that comes down to hunting old ground with a machine that hits small targets reliably. If your detector struggles with thin rings and fine chains, browse our metal detectors or start with our guide to the best beach detectors, since beaches replenish their gold supply every summer weekend.

Dug something with a stamp this guide doesn't cover? Send us a photo. Chances are one of us has dug one too.