900 usually means platinum 900 (PT900), 90% pure platinum. On older American silver it means coin silver, 90% silver.
PT900, PT 900, COIN on old American silver
PT900 is common in Japanese jewelry. Coin silver appears on American spoons and jewelry from the 1800s.
| Platinum 900 | Melt value |
|---|---|
| 2 gram piece | $102.90 |
| 5 gram piece | $257.24 |
| 10 gram piece | $514.48 |
Weigh your piece in grams on a kitchen or jewelry scale. Set stones add weight, so the real figure is a little lower. A buyer pays less than melt to cover refining and profit. Melt value calculator
Stones, a known maker or antique design can be worth far more than the metal. Photograph your piece and GemstoneAI identifies it and estimates what it is worth. Your first scan is free.
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A stamp is a claim, not proof. Fake jewelry is sometimes stamped with real-looking marks. In the US, a purity mark is supposed to sit next to a maker's trademark, so a purity stamp on its own deserves a closer look.
More checks: how to tell if gold is real and the 5-question ring checker.
PT900 is platinum. A plain 900 or COIN mark on old American pieces is coin silver.
About $51.45 per gram at melt today.
No. Stamps are easy to fake. Back a stamp up with a magnet, a look at worn edges, or a jeweler's test before you rely on it.