Platinum is classified according to the percentage of platinum weight in the product. That is, PT850 is 85% platinum by weight, PT900 is 90% platinum by weight, and PT950 is 95% platinum by weight.
In countries like the United Kingdom, the fineness for Platinum is classified as 850, 900, 950, and 999, with the highest platinum grade and the most common purity being Platinum 950. The best quality platinum used in jewellery is PL950 as anything less than that doesn’t last long, and also wears with time.
However, platinum (PL950) is graded according to:
1. PL950/Iridium: Made up of 95% platinum and 5% iridium by weight. It can be regarded as 100% precious as iridium is one of the platinum group metals, although it’s not considered the highest quality of grades. This metal mixture is soft and as such, can bend and scratch. Over time, this type of platinum can look dull or take a lot of scratches.
2. PL950/Ruthenium: Made up of 95% platinum and 5% ruthenium by weight. It can also be regarded as 100% precious as ruthenium is one of the platinum group metals. This metal mixture is durable, it’s almost scratch resistant and can achieve a beautiful mirror polish.
3. PL950/Cobalt: Made up of 95% platinum and 5% ruthenium by weight. This type isn’t 100% precious, although it’s considered superior and has the highest quality of platinum compared to other platinum grades. This metal mixture is strong and durable, can be made into different shapes and designs, and offers incredible brilliance.