PLATINUM
Rare and precious
Platinum is the chemical element with atomic number 78 and the symbol Pt. It belongs to the family of transition metals and is part of the “platinum group,” which includes ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir). Along with silver, gold, and palladium, it is recognised and regulated as a precious metal by the Swiss Precious Metals Control. In 2023, South Africa extracted 120 tonnes of platinum, representing 69% of the global production (175 tonnes)*.
Platinum is often naturally alloyed with other metals and extracted from ores such as sperrylite (PtAs₂).
Properties
Platinum is malleable and ductile, offering good resistance to oxidation, corrosion, and abrasion. Chemically very stable, it is hypoallergenic.
In watchmaking and jewellery, platinum is prized for its white colour, which enhances the setting of precious stones without altering their natural hue. However, working with platinum is challenging, as its alloys cause rapid tool wear and the brittle chips it produces make it unpopular with engravers.
Alloys and names
In its pure form, platinum is too malleable for watchmaking or jewellery use, so it is typically mixed with other elements to produce a suitable alloy. In horology, platinum is typically used with a purity of 950/1000, often combined with ruthenium, whereas in jewellery, platinum blends are favoured for casting.
The first objects made of platinum and its initial descriptions date back to the 14th century CE. Platinum was studied during the 18th century, but it wasn’t until 1803 that it was recognised as a chemical element and classified accordingly. By the 18th century, platinum began to be used in both jewellery and watchmaking.
Platinum’s resistance to corrosion, oxidation, and abrasion, along with its distinctive colour, makes it highly valued for the production of external watch components (cases, bracelets, clasps, etc.). Its density and non-magnetic properties make it suitable for the manufacture of oscillating weights and balance screws, for example. However, because of its density, platinum is not an efficient conductor of sound, making it less suitable for use in chiming watch cases.