| Description: | When used in jewellery, platinum is commonly alloyed (900 or 950 platinum) with cobalt, iridium, or ruthenium for increased hardness. For a jewellery piece to be labelled as “platinum†or “PLAT†it must have a “fineness†(millesimal fineness) of at least 95% pure platinum.
If the fineness falls below the 95% mark, it must be labelled “IRIDPLAT†which would indicate a platinum alloy with at least 10% Iridium. Platinum is graded as: 850 sterling, 900 sterling, 950 sterling, and 999, which is identified and stamped using the precious metals hallmarking system. However, Platinum 950 is the most common purity for platinum jewellery in Australia and around the world.
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