Diamonds, gold and platinum are among the most valuable substances on the planet – but so are painite, the chemical Californium 252 and a host of other obscure materials you’ve probably never heard of. These items command a high price for the fact they’re ultra-rare, hard to extract or valued for highly unique properties. Click or scroll through to discover the most valuable substances on earth and why they're so prized. Prices correct at the time of writing (24th January 2020).