Platinum prices have hit highs not seen for more than 25 years, driven by growing demand for the metal in cleaning car exhausts.
Platinum is a key component in cleaning diesel engine exhausts
Prices have risen nearly 130% over the past four years and now stand at more than $950 per troy ounce.
World demand for platinum is currently outstripping supply.
It is a key component for catalytic converters in car engines, and use is growing as pollution rules are toughened.
Russia and South Africa are the two main producers of platinum.
Demand for a similar precious metal, palladium, is also rising because it is being used as a cheaper alternative for jewellery, particularly in China.
Prices for palladium, which can also be used to clean car engine exhausts, now stand at about $240 per troy ounce.