PT950 (platinum)

How to read it

The FTC’s jewelry guides allow Plat. or Pt. as the abbreviation for platinum, and allow metal of at least 950 parts per thousand pure platinum to be marked platinum with no number at all. Metal of 850, 900 or 950 parts per thousand may be marked platinum with the number before it; the guides’ own examples are 950Pt., 950Plat., 900Pt., 900Plat., 850Pt. and 850Plat. PT950 puts the same abbreviation and number the other way round. The FTC’s consumer guide gives the plain word platinum as meaning at least 95% pure platinum.

Also searched as: 950 Plat, Plat, PT900, Pt950, PT950.

Platinum in UK hallmarks

The UK’s Hallmarking Act lists four platinum standards, 850, 900, 950 and 999, and gives 950 and 999 platinum an optional picture mark of its own: an orb surmounted by a cross. Platinum is newer to British hallmarking than gold or silver. Birmingham Assay Office’s timeline dates platinum becoming a hallmarkable metal to 1975, and the Act still exempts articles wholly or mainly of platinum made before 1 January 1975. Sheffield Assay Office did not assay platinum until June 1975. Until 1999 the lowest platinum standard was 950; the 1998 amendment regulations lowered the minimum to 850.

PT950, 950 silver and 950 palladium

The number 950 on its own does not say which metal. In a UK hallmark, 950 is a standard for both platinum and palladium, and the assay offices’ guidance notes say the metal is shown by the shape of the shield around the number. Palladium’s optional picture mark is the head of Pallas Athene; platinum’s is the orb. There is no 950 silver standard in the Act, which marks silver at 800, 925, 958 or 999. In the US, the FTC’s guides give palladium its own abbreviations, Pall. and Pd., so a US mark names the metal in letters.

Platinum alloys under 850

Below 850 the FTC’s guides ask for more. A product that is at least 500 but less than 850 parts per thousand platinum, and not at least 950 parts per thousand platinum group metals, may be marked with parts per thousand and chemical abbreviations, their example being 585 Pt., 415 Co. The guides list 600Plat. as misleading when the other platinum group metals in the piece are not named, and say the word platinum should not be used at all for anything under 500 parts per thousand pure platinum. In its 2018 review the FTC kept these platinum thresholds unchanged, saying consumers expect platinum products to be substantially composed of pure platinum.

Platinum with other platinum group metals

The FTC’s guides name six platinum group metals: platinum, iridium, palladium, ruthenium, rhodium and osmium. Metal that is at least 950 parts per thousand platinum group metals, and at least 500 platinum, may be marked with each metal’s share, as in 600Pt.350Ir. or 550Pt.350Pd.50Ir.

Platinum and rhodium plating

The FTC’s guides call it deceptive to fail to disclose a surface layer of rhodium on products marked or described as precious metal. A platinum-coloured finish is not a platinum mark: the guides say the word platinum on a product with only a surface layer of platinum should be qualified to show it is only coated.

Small pieces

The UK’s exemption weight for platinum is the lowest of the four metals: articles under 0.5 grams need no hallmark. Pt 950 is one of the five standards the Hallmarking Convention says are legal in every member state.

Solder and small parts

The UK assay offices’ table requires solder in 950 platinum to be precious metal of a combined fineness of at least 950, and the 1998 amendment regulations tied platinum solder to the standard of fineness of the article, where it had been a flat 950. The FTC’s guides list parts left out of any assay of a platinum product, including springs, screws, rivets and bracelet and necklace snap tongues.