Gold Hallmark Identifier
Convert karat, fineness and gold percentage (18K = 750 = 75.0%), decode a typed stamp and find the pure gold in an item by weight. How it works
Use the Gold Hallmark Identifier
About the Gold Hallmark Identifier
750 on gold means 750 parts per thousand, which is 18K and 75.0% pure gold: karat = fineness × 24 ÷ 1000 and percentage = fineness ÷ 10. This gold hallmark identifier converts karat, fineness and gold percentage in any direction, decodes a typed stamp such as 750, 585 or 18K, and gives the pure gold in an item from its weight: 10 g of 14K (585) holds 5.85 g of gold.
Karat, fineness and gold percentage
| Karat | Fineness (stamp) | Gold % | Karat shown if the stamp is typed | Pure gold in 10 g |
|---|---|---|---|---|
| 9K | 375 | 37.5% | 9K | 3.75 g |
| 10K | 417 | 41.7% | 10.01K | 4.17 g |
| 12K | 500 | 50.0% | 12K | 5.00 g |
| 14K | 585 | 58.5% | 14.04K | 5.85 g |
| 18K | 750 | 75.0% | 18K | 7.50 g |
| 20K | 833 | 83.3% | 19.99K | 8.33 g |
| 21K | 875 | 87.5% | 21K | 8.75 g |
| 22K | 916 | 91.6% | 21.98K | 9.16 g |
| 23K | 958 | 95.8% | 22.99K | 9.58 g |
| 24K | 999 | 99.9% | 23.98K | 9.99 g |
The stamp for each karat is the one the page’s Karat select uses. Typing a stamp reads it exactly: fineness × 24 ÷ 1000, shown to 2 decimals. The ranking badge groups 10K and below as Low, above 10K to 14K as Medium, above 14K to 22K as High and above 22K as Pure; it is the page’s own grouping, not a standard.
How to use this tool
- Type a stamp in the Hallmark Stamp field, pick a karat, or enter a fineness or a gold percentage. The field you edit last sets the purity and the others show what it means.
- Add the item’s weight and choose g, oz, dwt or kg to see the pure gold it holds.
- Read the headline, such as 750 = 18K = 75.0% pure gold. A stamp of 925, 950 or 960 shows a message that it looks like a non-gold metal.
Frequently asked questions
- What does 750 mean on gold?
- 750 is the fineness: 750 parts of gold per 1,000 parts of metal, or 75.0% gold. As a karat it is 750 × 24 ÷ 1000 = 18K. Typing 750 in the stamp field shows 750 = 18K = 75.0% pure gold. The table above lists the stamp for each karat from 9K to 24K.
- How do I convert karat to percent gold?
- Divide the karat by 24 and multiply by 100: 18K is 18 ÷ 24 × 100 = 75.0%. For 14K the exact figure is 58.3333%, but the stamp for 14K is 585, and the Karat select uses the stamp, so 14K shows 585 = 14K = 58.5% pure gold. To use the exact figure, type 583.3 as the fineness: it shows 583.3 = 14K = 58.3% pure gold.
- Why does a typed 585 show as 14.04K?
- A typed stamp is read exactly: 585 × 24 ÷ 1000 = 14.04. The 14K row of the table uses 585 as its stamp even though 14K is exactly 583.3 fine. To get the table row, pick 14K in the Karat select. The 22K row works the same way: a typed 916 is 21.98K, while the select shows 916 = 22K.
- How much pure gold is in my ring or chain?
- Pure gold = weight × fineness ÷ 1000. A 10 g item stamped 585 holds 5.85 g of gold, one stamped 750 holds 7.50 g and one stamped 916 holds 9.16 g. The answer is in the unit you pick (g, oz, dwt or kg), with no conversion between units, and weights run from above 0 up to 10,000. It is a gold content, not a price.
- What if my gold is not a standard karat, such as 80%?
- Type it. A fineness of 800 or a gold percentage of 80 shows 800 = 19.2K = 80.0% pure gold, and 70% shows 700 = 16.8K = 70.0% pure gold. The Karat select then shows 19.2K (not a table karat) as its placeholder. Fineness has to be from 375 to 1000 and gold percentage from 37.5 to 100.
- Can this tool tell me whether a hallmark is real or what a country symbol means?
- No. It decodes the number you type and does not verify that a mark is genuine. The Country menu only filters the symbols table and does not change the purity. That table has a few rows read from assay office and customs pages (the UK crown with 18 or 22 used before 1975 and the fineness numbers since, German gold with a number only, the Swiss St. Bernhard head) and the rest are labeled unverified, so do not rely on those. For a question of authenticity or origin, ask an assay office or a qualified jeweler.
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