Gold Karat Stamps & Hallmarks Explained
Published June 19, 2026 · updated June 19, 2026
That tiny number pressed into the inside of your gold ring or the clasp of a chain tells you how much actual gold the piece contains. Karat stamps and hallmarks are the first thing to look at when you want to understand what your gold is worth, because karat purity is one half of the value equation. The other half is weight, and the live spot price does the rest. If you want to skip ahead and see the math, plug your numbers into our gold calculator.
What a karat stamp actually means
A karat measures purity, not weight. Pure gold is 24 karat (24K), which is 99.9% gold. Everything below that is gold mixed with harder metals like copper, silver, or zinc to make the alloy durable enough for daily wear. The stamp tells you the percentage of pure gold in the piece:
- 24K = 99.9% gold
- 22K = 91.67% gold
- 18K = 75% gold
- 14K = 58.5% gold
- 10K = 41.67% gold
So when you see a 14K stamp, just over half of that item by weight is real gold and the rest is alloy. That is why two rings of identical size can be worth very different amounts.
The three-digit hallmark system
Many pieces, especially imported or older ones, use a three-digit number instead of the “K” stamp. This is a millesimal fineness hallmark, and it is simply the purity written as parts per thousand:
- 999 = 24K (99.9%)
- 916 or 917 = 22K (91.67%)
- 750 = 18K (75%)
- 585 = 14K (58.5%)
- 417 = 10K (41.67%)
A stamp reading 585 and a stamp reading 14K describe the exact same alloy. Knowing both systems saves you from mistaking a foreign hallmark for a lower value. You can see today’s value per gram for a common karat on our 14K gold price per gram page.
How to find and read the stamp
On rings, the stamp is usually on the inside of the band. On chains and bracelets, check near the clasp or on a small tag soldered to the end. Earrings often carry the mark on the post. Use good light and a loupe or phone camera zoom, because older marks can be worn flat. Look for a maker’s mark or country hallmark nearby, which can also hint at quality standards.
A quick way to estimate value from the stamp
Once you know the karat, you only need the weight and the spot price. A jeweler’s scale gives weight in grams. There are 31.1034768 grams in one troy ounce, and one pennyweight (dwt) equals 1.55517 grams, so you can convert either way. Multiply the weight by the karat purity fraction and then by the current gold price per gram. The result is the melt value, not an offer, but it is your best reality check before you sell.
Frequently Asked Questions
Does a stamp guarantee the karat? A stamp is a strong indicator but not a guarantee. Reputable sellers and assay offices are reliable, but the only way to be certain is a professional acid, electronic, or XRF test.
What does “GF,” “GP,” or “HGE” mean? These mean gold-filled, gold-plated, or heavy gold electroplate. Only a thin layer of gold covers a base metal, so the melt value is far below what a solid karat stamp would suggest.
Is unstamped gold still real? Yes. Older, handmade, or resized jewelry often loses its stamp. Have an unstamped piece tested rather than assuming it is fake, because genuine karat gold can carry no mark at all.