Gold jewelry stamps: what 14K, 585 and GF mean

Where to find the stamp

Gold marks are tiny and usually hidden: inside a ring's band, on a chain's clasp or the small tag beside it, on an earring post, or on the back of a pendant. Zoom in with your phone's camera or a magnifying glass.

Karat marks and their number equivalents

Karat measures gold in parts out of 24. 24K is pure gold; 14K is 14 parts gold and 10 parts other metals such as silver, copper and zinc. Much of the world writes the same thing in parts per thousand instead.

So what does 585 mean on gold? It means 14K. Exact 14K works out to 58.3%, and the 585 standard sits just above it. In the same way, 750 is 18K and 375 is 9K.

In the US, a piece may fall short of its stamp by no more than three parts per thousand, or seven for most jewelry when the solder is tested along with it.

Marks that mean plated or filled

These mean a layer of gold over another metal. Any karat number in the mark describes only that layer, not the whole piece, which is why "18K GP" is not 18K gold.

• GF, or "gold filled". A layer of gold alloy bonded to a base metal core, usually brass. Under US guidelines the gold must be at least 1/20 of the total metal weight. A mark like 1/20 12K GF means at least one-twentieth of the weight is 12K gold.
• RGP, "rolled gold plate" or "gold overlay". The same idea with a thinner layer, at least 1/40 by weight, as in 1/40 10K RGP.
• GP, GEP or EP. Gold plate or gold electroplate, a thin surface layer. "Gold electroplate" needs only 0.175 microns of fine gold under US guidelines, far thinner than gold filled.
• HGE or HGP, usually read as heavy gold electroplate and heavy gold plate. US guidelines call for at least 2.5 microns of fine gold for "heavy gold electroplate". Heavier, but still plate.
• Vermeil. Sterling silver coated with gold of at least 10K, at least 2.5 microns thick. These pieces are often also stamped 925, the sterling mark.

The gold in plated and filled pieces is small, so they sell on style and maker rather than on weight.

Maker's marks, and why a stamp alone isn't proof

Next to the karat mark there is often a name, initials or a logo. In the US, anyone who stamps a karat or fineness mark on gold that is shipped between states or imported must also stamp a trademark or name beside it. A maker's mark tells you who made the piece, and a well-known one can add real value.

But a stamp is only a claim, struck by whoever made the piece. British hallmarks are applied by an independent assay office after testing; US karat marks are applied by the maker, with no outside check. Treat the stamp as the start of the answer, not the end.

Signs of a fake or misleading stamp

• Poor striking: shallow, crooked or uneven characters, or marks that look scratched in rather than stamped.
• Marks that disagree, such as 14K beside 750.
• Letters after the karat: 14K GP, 18KGE, 14K HGE. The karat describes only the plating.
• 925 on a gold-coloured piece. That is gold over silver, not solid gold.
• A karat mark with no maker's mark on a modern piece sold in the US. Not proof of a fake, but worth a closer look.
• A stamp only on the clasp. Clasps are sometimes replaced or made separately, so check the chain itself.

Simple checks that don't harm the piece

• Magnet: gold is not magnetic. If a strong magnet pulls firmly at the piece, it is not solid gold. Test the chain or band, not the clasp, which may hold a small steel spring. Passing doesn't prove gold: brass isn't magnetic either.
• Colour where it's worn: look at edges, the inside of a ring and links that rub. Solid gold is the same colour all the way through. Plated and filled pieces wear through to brass, copper or silver.
• Weight: gold is one of the densest metals, so a solid piece feels heavy for its size. A large piece that feels light is often hollow or plated. Hollow gold is real gold, just less of it.

Leave acid tests to a jeweler. An acid test means rubbing the piece on a testing stone or filing a small notch, then applying strong acid. It removes metal, can leave a mark, and the acids are hazardous. A thick plating can also pass a test made only on the surface. Many jewelers also have electronic testers that don't scratch.

How weight and purity set the melt value

Plain gold with no special maker or design is priced mostly by its metal:

Melt value = weight × purity × spot price

Weigh the piece in grams. Multiply by its purity: 0.585 for 14K, 0.75 for 18K. That gives the weight of pure gold, so 10 grams of 14K holds about 5.85 grams. Multiply that by the day's spot price per gram. Spot is usually quoted per troy ounce, which is about 31.1 grams, so divide the ounce price by 31.1 first.

Two cautions. Remove or allow for any stones, because a diamond or a glass bead adds weight that isn't gold. And buyers rarely pay full melt, because refining costs money. Get more than one offer, and sort pieces by karat so they aren't all priced as the lowest.

When a piece is worth more than its gold

• The maker. Signed pieces from well-known jewelry houses, such as Tiffany & Co. or Cartier, often sell for far more than their weight. They are also the most copied, so a famous name needs checking.
• Design and workmanship: fine engraving, enamel, unusual construction, or a recognisable designer's style.
• The era. Victorian, Art Nouveau, Art Deco and mid-century pieces have collectors of their own.
• Gemstones. Stones are valued separately, and a good one can be worth more than the gold around it.

If a piece has any of these, don't sell it for scrap. Compare sold prices for similar pieces, and for anything valuable, have a qualified jeweler or appraiser examine it in person.

Related guides

• How to read silver hallmarks
• How to tell if a watch is fake
• How to value inherited antiques

Worthzy gives estimates and an authenticity screening, not a certified appraisal. For anything valuable, have a qualified specialist examine it in person.