Is CASTLE the same as Edinburgh Castle?

Yes. CASTLE, Edinburgh Castle, THREE TOWER CASTLE all denote the same material — assay-mark. Different markets and eras stamp it differently, but the purity is identical.

How do I confirm a CASTLE 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, scan it with the Jewelry Identifier app, and — when it matters — have an XRF test done by an assay office or gemological lab.

* assay-mark hallmark

The CASTLE hallmark: meaning, purity & value

British assay office mark: three-towered castle indicates Edinburgh Assay Office (Scotland, established 1457). Used continuously since the 15th century.

Published May 30, 2026

Quick facts

Metal: assay-mark
Common regions: UK

Stamps that mean the same thing

This purity may be struck into jewelry as any of: CASTLE / Edinburgh Castle / THREE TOWER CASTLE. The mark differs by country and era, but the metal content is identical.

What CASTLE tells you

British assay office mark: three-towered castle indicates Edinburgh Assay Office (Scotland, established 1457). Used continuously since the 15th century.

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 CASTLE or an equivalent such as Edinburgh Castle.
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

Edinburgh Assay Office records

* Frequently asked

FAQ

Q. Is CASTLE the same as Edinburgh Castle?: A. Yes. CASTLE, Edinburgh Castle, THREE TOWER CASTLE all denote the same material — assay-mark. Different markets and eras stamp it differently, but the purity is identical.
Q. How do I confirm a CASTLE 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, 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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