What does PLAT mean on jewelry?
Short answer
950 platinum (unqualified "platinum" requires 950 in the US).
A mark is a statement, not proof: it can be forged or struck on a plated piece. An assay confirms it (touchstone and acids, or X-ray fluorescence).
The stamp in detail
| Item | What the tables say |
|---|---|
| Stamp | PLAT |
| Class | Fineness (purity) mark |
| Platinum fineness | 950 parts per thousand (95 % platinum) |
| Legal standard (platinum 950) | United Kingdom, Vienna Convention states, France, United States |
| Source check | Checked against the sources listed below |
| Date clue | Not before 1900. Platinum did not become usual in jewelry until about 1900. |
What is PLAT worth by weight?
Every gram of a piece stamped PLAT holds 0.95 g of fine platinum, if the stamp is accurate. Multiply that by the spot price of platinum to get the melt value. It is the floor, what the metal is worth if melted, not what a buyer will pay and not an appraisal.
Example, clearly not live: 10 g at the example price of $1,555.00 per troy ounce (snapshot of 2026-11-10) is $474.95. The working: 10 g → 950 / 1000 → 10 g × 0.95 → 1555 USD/ozt ÷ 31.1034768 g/ozt → 9.5 g × 49.9944 USD/g.
Melt value calculator for PLAT
Enter a weight and a stamp to see the sum.
Today's spot price: LBMA precious metal prices, Kitco live gold or your own dealer's quote. This page never contacts a price service.
Related stamps
Other ways the same fineness is stamped: 950, PT950.
Frequently asked
What does PLAT mean on jewelry?
950 platinum (unqualified "platinum" requires 950 in the US).
Does PLAT mean the piece is solid platinum?
It means the piece is stamped as platinum, 950 parts per thousand. A mark is a statement, not proof: it can be forged or struck on a plated piece. An assay confirms it (touchstone and acids, or X-ray fluorescence).
How much fine platinum is in a piece stamped PLAT?
0.95 g of fine platinum per gram of metal, if the stamp is accurate. Melt value is that weight times the spot price. It is not an appraisal.
Sources
- FTC Jewelry Guides, 16 CFR 23.6 (platinum)
- Hallmarking Act 1973, Schedule 2 (revised text)
- Vienna Convention on precious metals, Technical Decisions Rev. 13 (in force 1 Oct 2026)
- Douane française, table of guarantee marks (2009)
All sources are listed with the method on the sources page.