* ruthenium hallmark
The Ru hallmark: meaning, purity & value
Ruthenium. Alloying element in platinum (Pt-Ru) to improve hardness for prong settings. Rare as standalone jewelry metal.
Published May 30, 2026
Quick facts
- Metal
- ruthenium
- Common regions
- international
- Density
- 12.45 g/cm³
- Melting point
- 2334 °C
Stamps that mean the same thing
This purity may be struck into jewelry as any of: Ru / RUTHENIUM. The mark differs by country and era, but the metal content is identical.
What Ru tells you
Ruthenium. Alloying element in platinum (Pt-Ru) to improve hardness for prong settings. Rare as standalone jewelry metal.
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 Ru or an equivalent such as RUTHENIUM.
- Weigh the piece and estimate its volume — the density should land near 12.45 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 Ru the same as RUTHENIUM?
- A. Yes. Ru, RUTHENIUM all denote the same material — ruthenium. Different markets and eras stamp it differently, but the purity is identical.
- Q. How do I confirm a Ru 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 (12.45 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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