Diamond specialists De Beers has rolled out a new machine to prove the authenticity of diamonds to ward off the threat of synthetic stones masquerading as real ones.

At an event in Hong Kong, the International Institute of Diamond Grading & Research (IIDGR), part of the De Beers diamond group that parent Anglo American has said is central to its operations, launched new equipment that can screen thousands of tiny diamonds, known as melee, and determine whether they are genuine.

It says it expects over the next two years to sell around 500 of the machines at $45,000 each.

The devices, which screen diamonds 10 times faster than the previous model, are sold to jewellers across the world as De Beers seeks to set industry-wide standards and prevent anyone passing off a laboratory-grown stone as natural.

It could in theory be easy to conceal small synthetic stones in a melee.

Jonathan Kendall, president of IIDGR, said synthetic stones were still only a small percentage of global diamond production, but De Beers needed to be ahead of any reputational threat.

"We are making sure we cover any future issue that may arise," Kendall told Reuters by phone. "Confidence is everything in the diamond sector."

The rough diamond market, in which De Beers is the biggest player by value, fell sharply in 2015 in line with a wider commodity price collapse, but recovered in 2016.

On Tuesday, De Beers said its latest sale of rough stones achieved $545 million, down from $617 million the same time a year ago.