In the US, gold purity is usually stamped in karats: 10K is 41.7% gold, 14K is 58.5%, 18K is 75% and 24K is practically pure gold. The same purity can also appear as a fineness number in thousandths, such as 417, 585 or 750. Multiply an item’s weight by its purity and you get the amount of pure gold, which is what its metal value is based on.
Karats and fineness at a glance
The karat scale divides gold into 24 parts. A 14K chain is 14 parts gold and 10 parts other metals such as silver, copper, zinc or palladium. European-made jewelry and bullion usually show fineness in thousandths instead, so it helps to know both systems.
| Karat | Fineness stamp | Pure gold | Where you typically see it |
|---|---|---|---|
| 10K | 417 | 41.7% | Class rings, budget jewelry |
| 14K | 585 | 58.5% | The most common karat for US jewelry |
| 18K | 750 | 75% | Fine jewelry, watches, engagement rings |
| 22K | 916 / 917 | 91.6–91.7% | American Gold Eagle, Krugerrand, some imported jewelry |
| 24K | 999 / 9999 | 99.9% or more | Bullion bars, American Gold Buffalo, Canadian Maple Leaf |
The extra metals are there on purpose. They make gold harder and set its color: copper produces rose gold, while palladium or nickel help produce white gold. A 14K ring stands up to daily wear far better than a 24K one, but it contains much less gold.
How US gold markings work
The US has no government assay office that tests and hallmarks jewelry, as the UK does. Instead, markings are governed by federal rules:
- The National Gold and Silver Stamping Act sets accuracy requirements for quality marks such as “14K”, and a quality mark on a gold article must be accompanied by the registered trademark of the maker or seller who stands behind it.
- The FTC Jewelry Guides (16 CFR Part 23) say gold products should be described with their karat fineness. Calling something simply “gold” implies 24-karat gold.
In practice, a genuine US stamp looks like “14K” or “585” next to a maker’s trademark. A karat stamp on its own is a red flag that the item should be tested, but it is not proof of a fake: older or imported pieces are sometimes stamped differently.
Coins: purity comes from the mint
Bullion and older circulating coins are not stamped like jewelry. Their purity is fixed by law or by the issuing mint:
- American Gold Eagle (1 oz) – 22K (91.67%), gross weight 33.931 g, containing exactly one troy ounce (31.1 g) of pure gold. It has been minted since 1986.
- American Gold Buffalo (1 oz) – 24K (.9999 fine), one troy ounce of pure gold, minted since 2006.
- Krugerrand (1 oz) – 22K, about 33.93 g gross, one troy ounce of pure gold.
- Pre-1933 US gold coins – such as the $20 Double Eagle, are .900 fine (about 21.6K).
The key point: a 22K one-ounce coin weighs more than a 24K one-ounce coin because of the alloy, yet both hold the same ounce of gold. Live prices for these coins are on our US gold prices page.
Working out how much gold you actually have
The formula: weight in grams × purity = grams of pure gold. (Jewelers often weigh in pennyweights; one pennyweight, dwt, is 1.555 g.)
- A 20 g 14K chain: 20 × 0.585 = 11.7 g of pure gold.
- A 5 g 10K class ring: 5 × 0.417 = about 2.1 g of pure gold.
- An 8 g 18K band: 8 × 0.750 = 6 g of pure gold.
Multiply the result by the current price per gram of pure gold to get the melt value. Our gold calculator runs the numbers for any karat. Remember that stones, springs and clasps may be counted in the weight, and a buyer will usually deduct them.
Markings that do not mean solid gold
Several common stamps describe a thin layer of gold over another metal:
- GP, GEP, HGE – gold plated or heavy gold electroplate: a very thin layer of gold on base metal.
- GF, 1/20 14K GF – gold filled: a thicker gold layer bonded to base metal, but most of the item is not gold.
- RGP – rolled gold plate, similar to gold filled with a thinner layer.
- Vermeil or 925 on a yellow item – sterling silver coated with gold.
- “14K” with no trademark – not necessarily fake, but worth testing.
These items have value as jewelry, but very little as gold, and a gold buyer will treat them accordingly.
Color is not a reliable guide to karat. Yellow 10K and yellow 18K can look almost identical once polished, and white gold is often rhodium plated, which hides the underlying alloy completely. The stamp, the maker’s trademark and, if in doubt, a test by a jeweler are what tell you the purity.
What purity means for buying and selling
When you sell, buyers price items by their pure gold content and then apply their own margin. Two 10 g items can be worth very different amounts: an 18K piece contains about 1.8 times as much gold as a 10K piece. When you buy jewelry, higher karats cost more per gram but carry more metal value; for coins and bars the meaningful comparison is the premium over the gold content. You can compare dealers on our US bullion dealers page.
Bottom line
Karats measure gold in 24ths and fineness measures it in thousandths: 10K, 14K, 18K and 24K correspond to 417, 585, 750 and 999. US quality marks must come with a registered trademark, while coins follow their mint specification. Pure gold content equals weight × purity.
Sources: 16 CFR Part 23 – FTC Jewelry Guides · 15 U.S.C. Chapter 8 – National Gold and Silver Stamping Act · U.S. Mint
This is general information, not tax or investment advice.
Frequently asked questions
How much gold is in 14K gold?
14K gold is 58.5% pure gold. A 10 g 14K item contains about 5.85 g of pure gold.
What does 585 stamped on gold mean?
585 is the fineness mark for 14 karat gold. It means 585 parts per thousand of the alloy are pure gold.
Is a 22K American Gold Eagle worth less than a 24K Buffalo?
Both one-ounce coins contain exactly one troy ounce of pure gold. The Eagle is heavier because of its alloy; their prices differ mainly by premium.
What does GF or HGE mean on jewelry?
GF means gold filled and HGE means heavy gold electroplate. Both are layers of gold over another metal, not solid gold.
Does US gold jewelry have to be hallmarked?
There is no government hallmarking system in the US. If a quality mark such as 14K is applied, federal law requires it to be accurate and accompanied by a registered trademark.
