Pt950 Platinum
Pt950 Platinum
The Western fine-jewellery default for platinum work
Pt950 platinum is a platinum jewellery alloy containing 950 parts per thousand of pure platinum (95%), with the remaining 5 per cent composed of alloying metals — typically ruthenium, iridium, or cobalt. Pt950 is the international standard for platinum fine jewellery in the United States, the United Kingdom, and most Western markets, and is the alloy assumed when a piece is sold simply as platinum in those markets.
Properties
The 95 per cent platinum content gives Pt950 the characteristic deep platinum-white colour, full corrosion resistance, hypoallergenic skin contact, and the noble-metal feel that buyers associate with fine platinum jewellery. The 5 per cent alloying-metal content is sufficient to harden the alloy from pure platinum's very soft baseline to a serviceable jewellery-grade hardness. Pt950 work-hardens further during fabrication, particularly under the hammer, the burnisher, and the polishing wheel, and reaches a useful working hardness in the finished piece.
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. Most production work uses Pt950Ru.
In the workshop
Pt950 is the standard fabrication metal for engagement rings, wedding bands, fine pendants, and high-end coloured-stone settings. Casting, rolling, drawing, soldering, and finishing are all conventional platinum-workshop operations at standard temperatures and pressures. Setters working in Pt950 take advantage of the alloy's ductility for prong work and rely on work hardening and burnishing to bring the prongs to the required stiffness for secure stone retention.
In the trade
Pt950 is the dominant platinum standard in the principal Anglophone fine-jewellery markets. Engagement rings and wedding bands are routinely produced to Pt950 specification, and the hallmark is the buyer's primary verification that a piece described as platinum meets the expected fineness. For pieces marketed in markets where lower platinum standards are also recognised, the trade convention is to specify Pt950 explicitly on retailer documentation.