Pt950
Pt950
The international standard for fine platinum jewellery
Pt950 is a platinum hallmark and fineness standard denoting 950 parts per thousand of pure platinum (95%), with the remaining 5 per cent composed of alloying metals such as ruthenium, iridium, or cobalt. Pt950 is the international standard for platinum fine jewellery in the United States, the United Kingdom, Canada, Australia, and most other principal Western markets, and is the de facto expectation when a piece is described simply as platinum in those markets. Japan recognises Pt950 alongside the lower Pt900 and Pt850 grades.
Properties
The 95 per cent platinum content gives Pt950 the deepest platinum-white colour and the highest tarnish and corrosion resistance of the common platinum jewellery alloys. The trade-off is hardness: with only 5 per cent alloying-metal content, Pt950 is softer than Pt900 or Pt850 and benefits from work hardening during fabrication and from periodic re-tipping of prong settings exposed to wear. The alloy is hypoallergenic and biocompatible, properties that contribute to its preference for engagement rings and other pieces in extended skin contact.
The choice of alloying metal — ruthenium, iridium, or cobalt — affects specific properties: Pt950Ru is the workshop standard, balancing hardness, workability, and cost; Pt950Ir is harder and better suited to high-wear prong applications; Pt950Co casts more cleanly into intricate moulds at the cost of weak ferromagnetism. All three formulations are recognised as Pt950.
Hallmarking and global standards
Pt950 is recognised under the United Kingdom Hallmarking Act, the United States Federal Trade Commission Jewelry Guides, the Plat-EU directives in the European Union, and equivalent regulations in Japan, Switzerland, and other major markets. The hallmark is typically stamped on the inside of the shank or on a discreet location on a finished piece, alongside the maker's mark and other regulatory marks required by the jurisdiction of origin. Buyers acquiring platinum jewellery should expect to find a Pt950 mark and should verify it on receipt.
In the trade
For dealers, retailers, and buyers operating in the principal Western fine-jewellery markets, Pt950 is the assumed standard. Engagement rings, wedding bands, and high-end fashion jewellery in platinum are routinely produced to Pt950 specification, with Pt950Ru the workshop standard for general fabrication and Pt950Ir for prong-intensive work. Where a piece is offered as platinum at a lower price than the Pt950 market would suggest, the buyer should look for the actual fineness stamp before assuming equivalence.