Is PLAT the same as PLATINUM?

Yes. PLAT, PLATINUM all denote the same material — platinum. Different markets and eras stamp it differently, but the purity is identical.

How do I confirm a PLAT stamp is genuine?

Look at the mark under 10× magnification for crisp, even strikes, cross-check the weight-to-volume ratio against the expected density (21.4 g/cm³ for this alloy), scan it with the Jewelry Identifier app, and — when it matters — have an XRF test done by an assay office or gemological lab.

* Platinum hallmark

The PLAT hallmark: meaning, purity & value

PLAT / PLATINUM marks platinum metal but may omit fineness. Prefer PT950/PT900/PT850 stamps for purity; melt needs a confirmed fineness.

Published May 30, 2026

Quick facts

Metal: Platinum
Common regions: United States, United Kingdom
Density: 21.4 g/cm³
Standard: ISO 9202

Stamps that mean the same thing

This purity may be struck into jewelry as any of: PLAT / PLATINUM. The mark differs by country and era, but the metal content is identical.

What PLAT tells you

PLAT / PLATINUM marks platinum metal but may omit fineness. Prefer PT950/PT900/PT850 stamps for purity; melt needs a confirmed fineness.

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 PLAT or an equivalent such as PLATINUM.
Weigh the piece and estimate its volume — the density should land near 21.4 g/cm³ for this alloy.
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.

Sources

ISO 9202
Trade hallmark references

* Frequently asked

FAQ

Q. Is PLAT the same as PLATINUM?: A. Yes. PLAT, PLATINUM all denote the same material — platinum. Different markets and eras stamp it differently, but the purity is identical.
Q. How do I confirm a PLAT 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 (21.4 g/cm³ for this alloy), 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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