How do you know your diamond isn’t fake?

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.

On the outer edge – what jewellers call the girdle – was a tiny inscription, of a bona fide diamond security code issued in 2015.

But the font was different to the one Gemological Institute of America, or GIA, uses.

And whereas the original diamond was natural, this diamond was grown in a lab.

“Rarely do we encounter the type of blatant fraud described here,” say Christopher Breeding and Troy Ardon from the Carlsbad lab.

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.”