Fake and irresponsibly sourced diamonds are undermining confidence in the industry – sales are down. Can new technologies, such as laser etching and blockchain, reassure an increasingly sceptical public? In a lab in the California city of Carlsbad, between Los Angeles and San Diego, a suspicious diamond recently arrived.
Diamonds are a huge business, with 133 million carats (about 27 tonnes) of rough diamonds worth about $15bn-$16bn (£12bn-£13bn) mined each year, according to Boston consulting firm Bain & Company.
About half originate in Africa, where in some countries, like South Africa and Botswana, mining is well regulated.
Carlsbad is the headquarters of the GIA, a non-profit organisation that evaluates and certifies diamonds for quality.
It assigns diamonds report numbers, which a laser can then carve on to the diamond. But this method has its problems.
“It is easy to be removed, just polish it off,” says Andrew Rimmer, chief executive of Opsydia, an Oxford University spin-out. “Also it’s easy to apply someone else’s serial number.”
In response, many people in the diamond industry have been working on using the blockchain – a tamper-proof distributed ledger – to store information on a gem’s history, from the mine to the jewellery shop.
Examples are Australia’s Everledger and De Beers’ Tracr. Russian diamond mining giant Alrosa announced last autumn it will join the Tracr platform.
Putting a full account of a diamond’s provenance on to a blockchain offers an “extremely secure way of storing detailed information”, says Opsydia’s Mr Rimmer. “But you still need to make sure the stone is the one it purports to be.”
So how can you write a permanent, tamper-proof security code inside a diamond?
Engineers at Oxford were doing research around focusing lasers on targets that are very small.
Marks as small as one-thousandth of a millimetre can be made 0.15mm below a diamond’s surface in a trillionth of a second. The extremely high speed keeps the laser burst from heating up the stone.
Marks this small can’t be seen even with a jeweller’s magnifying glass, or loupe and cannot be removed since it is beneath the surface. You need a powerful microscope.