* iridium hallmark
The Ir hallmark: meaning, purity & value
Iridium. Densest stable metal. Rare as standalone jewelry; common as alloying element in platinum (Pt-Ir alloy improves hardness).
Published May 30, 2026
Quick facts
- Metal
- iridium
- Common regions
- international
- Density
- 22.56 g/cm³
- Melting point
- 2466 °C
Stamps that mean the same thing
This purity may be struck into jewelry as any of: Ir / IRIDIUM. The mark differs by country and era, but the metal content is identical.
What Ir tells you
Iridium. Densest stable metal. Rare as standalone jewelry; common as alloying element in platinum (Pt-Ir alloy improves hardness).
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 Ir or an equivalent such as IRIDIUM.
- Weigh the piece and estimate its volume — the density should land near 22.56 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.
* Frequently asked
FAQ
- Q. Is Ir the same as IRIDIUM?
- A. Yes. Ir, IRIDIUM all denote the same material — iridium. Different markets and eras stamp it differently, but the purity is identical.
- Q. How do I confirm a Ir 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 (22.56 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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