Is 9K the same as K9?

Yes. 9K, K9, 375 all denote the same material — 37.5% gold. Different markets and eras stamp it differently, but the purity is identical.

How much is 9K worth?

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.

How do I confirm a 9K 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 (11.2 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.

* Gold hallmark

The 9K hallmark: meaning, purity & value

9K (375) is the UK/Australia minimum gold hallmark. Everyday jewelry standard; melt = spot × 0.375 × grams.

Published May 30, 2026

Quick facts

Metal: Gold
Purity: 37.5%
Fineness: 375/1000
Karat: 9K
Common regions: United Kingdom, AU
Density: 11.2 g/cm³
Standard: ISO 9202

Stamps that mean the same thing

This purity may be struck into jewelry as any of: 9K / K9 / 375. The mark differs by country and era, but the metal content is identical.

What 9K tells you

9K (375) is the UK/Australia minimum gold hallmark. Everyday jewelry standard; melt = spot × 0.375 × grams.

How to value it

The melt value of a 9K 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.

Live calculators: gold karat × weight · item × karat estimates · per-gram hub.

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 9K or an equivalent such as K9.
Weigh the piece and estimate its volume — the density should land near 11.2 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 9K the same as K9?: A. Yes. 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 9K 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 9K 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 (11.2 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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