Jewelry Hallmark Decoder
Type a fineness mark stamped on a piece of jewelry to find out what metal it is, how pure it is, and what the metal content is worth at any spot price. Nothing uploaded.
Decoded
Common stamp reference
Learn more: reading jewelry hallmarks and fineness stamps
What a fineness stamp tells you
A fineness stamp gives the metal's purity in parts per thousand. "925" is 92.5% silver (sterling), "750" is 75% gold (18 carat), "585" is 58.5% gold (14 carat) and "375" is 37.5% gold (9 carat). A 10 gram piece stamped 585 holds 5.85 grams of gold, and the rest is other metals for strength.
The decoder lists gold from 999 down to 375, silver from 999 to 800 and platinum from 999 to 850. Its metal value is weight times fineness times the spot price per gram, which ignores craftsmanship, brand, age and collector demand.
Some stamps mean the piece is not solid metal. "P" and "EP" mark plated or electroplated items with a thin coating over a base metal, and "GF" marks gold-filled, which has a thicker gold layer bonded to a base metal. None of them carry the melt value of a solid stamp.
Why a stamp alone is not proof
MetalsGems' guide to silver authentication says counterfeiters often stamp false marks or use low-grade alloys to mimic genuine pieces. It describes checks such as an acid test, judging weight and heft, and a magnet, since silver is not magnetic. A stamp shows what the maker claimed, so use it with other checks and a jeweler you trust.
UK assay office marks
Hemswell Antique Centres' guide to reading silver hallmarks lists the town marks: a leopard's head for London, an anchor for Birmingham, the castle for Edinburgh and, for Sheffield, a crown from 1773 to 1975 and a Tudor rose since. It says date letters show the year the piece was assayed, not made, and that each office has its own system of fonts and shield shapes.
FAQ
Why do UK hallmarks include a symbol like a leopard's head or an anchor?
It is the mark of the assay office that tested the piece, such as London (leopard's head) or Birmingham (anchor). It shows the metal was checked by an office, not only stamped by the maker.
Why do carat standards differ between countries?
Countries use different common purities for everyday jewelry. The decoder notes 9 carat (375) as common in the UK and Australia, 14 carat (585) in the USA and Germany, and 22 carat (916) as the sovereign standard.
Is metal value the same as what a piece is worth?
No. Metal value is weight times purity times the spot price. A piece can sell for more or less than that because of its design, maker, age and demand.