* Platinum hallmark
The Pt500 hallmark: meaning, purity & value
50% platinum. Rare in fine jewelry; sometimes appears in fashion pieces or as alloy backing.
Published May 30, 2026
Quick facts
- Metal
- Platinum
- Purity
- 50.0%
- Fineness
- 500/1000
- Common regions
- Japan
- Standard
- ISO 9202
Stamps that mean the same thing
This purity may be struck into jewelry as any of: Pt500 / PT500 / 500Pt. The mark differs by country and era, but the metal content is identical.
What Pt500 tells you
50% platinum. Rare in fine jewelry; sometimes appears in fashion pieces or as alloy backing.
How to value it
The melt value of a Pt500 piece is platinum spot price × 0.500 × weight (g). A buyer typically deducts 5–15% for assay, refining, and margin, so the cash offer lands just under that figure. Stones and complex settings are usually excluded from the metal weight.
How to check it yourself
- Examine the stamp under a 10× loupe — genuine marks are crisp and evenly struck, not doubled or smeared.
- Confirm the mark reads Pt500 or an equivalent such as PT500.
- Photograph it in the Jewelry Identifier app to read the metal, hallmark, and any gemstones from the image.
- For a binding result, have an assay office or gemological lab run an XRF purity test.
* Frequently asked
FAQ
- Q. Is Pt500 the same as PT500?
- A. Yes. Pt500, PT500, 500Pt all denote the same material — 50.0% platinum. Different markets and eras stamp it differently, but the purity is identical.
- Q. How much is Pt500 worth?
- A. Its melt value is the platinum spot price × 0.500 × the weight in grams. Buyers then deduct roughly 5–15% for refining and margin, so a quoted buy-back price sits a little below that theoretical figure.
- Q. How do I confirm a Pt500 stamp is genuine?
- A. Look at the mark under 10× magnification for crisp, even strikes, cross-check the weight-to-volume ratio against the expected density, scan it with the Jewelry Identifier app, and — when it matters — have an XRF test done by an assay office or gemological lab.
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