* Gold hallmark
The 375 hallmark: meaning, purity & value
9-karat gold fineness (37.5%). Minimum legal 'gold' in the UK and Commonwealth. Below US 10K minimum so it cannot be sold as 'gold' in the US.
Published May 30, 2026
Quick facts
- Metal
- Gold
- Purity
- 37.5%
- Fineness
- 375/1000
- Karat
- 9K
- Common regions
- UK, AU, NZ, IE
- Density
- 11.1 g/cm³
- Melting point
- 880 °C
- Standard
- ISO 9202
Stamps that mean the same thing
This purity may be struck into jewelry as any of: 375 / 9ct / 9K / K9 / .375. The mark differs by country and era, but the metal content is identical.
What 375 tells you
9-karat gold fineness (37.5%). Minimum legal 'gold' in the UK and Commonwealth. Below US 10K minimum so it cannot be sold as 'gold' in the US.
How to value it
The melt value of a 375 piece is gold spot price × 0.375 × 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 375 or an equivalent such as 9ct.
- Weigh the piece and estimate its volume — the density should land near 11.1 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
- UK Hallmarking Act 1973
- Wikidata Q21039
* Frequently asked
FAQ
- Q. Is 375 the same as 9ct?
- A. Yes. 375, 9ct, 9K, K9, .375 all denote the same material — 37.5% gold. Different markets and eras stamp it differently, but the purity is identical.
- Q. How much is 375 worth?
- A. Its melt value is the gold spot price × 0.375 × 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 375 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 (11.1 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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