Is K20 the same as 20K?

Yes. K20, 20K, 833, 20金 all denote the same material — 83.3% gold. Different markets and eras stamp it differently, but the purity is identical.

How much is K20 worth?

Its melt value is the gold spot price × 0.833 × 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 K20 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 (16.5 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 K20 hallmark: meaning, purity & value

20-karat gold (83.3%). Less common than K18; occasionally seen in Japanese vintage and antique pieces, and in some Russian Soviet-era jewelry alongside the 583 mark.

Published May 30, 2026

Quick facts

Metal: Gold
Purity: 83.3%
Fineness: 833/1000
Karat: 20K
Common regions: Japan
Density: 16.5 g/cm³
Melting point: 1010 °C
Standard: ISO 9202

Stamps that mean the same thing

This purity may be struck into jewelry as any of: K20 / 20K / 833 / 20金. The mark differs by country and era, but the metal content is identical.

What K20 tells you

20-karat gold (83.3%). Less common than K18; occasionally seen in Japanese vintage and antique pieces, and in some Russian Soviet-era jewelry alongside the 583 mark.

How to value it

The melt value of a K20 piece is gold spot price × 0.833 × 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 K20 or an equivalent such as 20K.
Weigh the piece and estimate its volume — the density should land near 16.5 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 K20 the same as 20K?: A. Yes. K20, 20K, 833, 20金 all denote the same material — 83.3% gold. Different markets and eras stamp it differently, but the purity is identical.
Q. How much is K20 worth?: A. Its melt value is the gold spot price × 0.833 × 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 K20 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 (16.5 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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