Hallmarks explained: Irish and UK marks

What a hallmark is, and is not

A hallmark is applied by an assay office, an independent body that tests the metal before striking the mark. That is what separates a hallmark from a maker simply stamping 925 or 18K on their own work. In Ireland, hallmarking is carried out by the Assay Office in Dublin, which has operated since 1637 and works from Dublin Castle. In the UK, four offices survive: London, Birmingham, Sheffield and Edinburgh.

The parts of an Irish hallmark

A full Irish hallmark on gold or silver typically includes a maker's or sponsor's mark, the initials of the firm that submitted the piece; a fineness mark showing the standard of the metal; and the mark of Hibernia, the seated female figure that identifies the Dublin office. Many pieces also carry a date letter that identifies the year of assay. On Irish silver you will often see the harp crowned as well, a standard mark with a long history on Dublin-assayed work.

The parts of a UK hallmark

Modern UK hallmarks have three compulsory elements: the sponsor's mark, a millesimal fineness number inside a shaped outline, and the assay office mark. The office symbols are the leopard's head for London, the anchor for Birmingham, the rose for Sheffield and the castle for Edinburgh. Older pieces usually add a date letter, and traditional standard symbols still appear: the lion passant for sterling silver, and a crown on older British gold.

Reading the fineness number

The single most useful part of any modern hallmark is the number. It states parts of precious metal per thousand. For gold: 375 means 9ct, 585 means 14ct, 750 means 18ct, 916 means 22ct and 999 is fine gold. For silver: 800 and 830 are continental standards, 925 is sterling, 958 is Britannia and 999 is fine silver. For platinum, 950 is the usual jewellery standard. Once you can find this number, you know exactly what the metal claims to be, and the price per gram follows directly from it, as our prices page shows product by product.

Foreign marks and convention marks

Ireland and the UK are both members of the international hallmarking convention, so items marked in other member countries with the convention's common control mark, a balance scale design, are recognised here. Beyond that, imported jewellery may carry anything from French eagle heads to plain numbers, and much of the gold sold worldwide carries a bare 750 or 18K stamped by the maker rather than an assay office.

When marks are missing, worn or wrong

Marks wear away on old rings, disappear when items are resized, and are occasionally faked. That is why a serious buyer never relies on the stamp alone. We test every item by XRF in front of you, whether it is fully hallmarked or completely blank, and price it on what the metal actually is. If you have a box of mixed and unmarked pieces, describe it on the sell page and we will sort the precious metal from the plate honestly.