DE BEERS is taking the threat posed by synthetic diamonds so seriously that it will not even call them diamonds, and has prevailed upon its clients to do the same.

Synthetic diamonds are grown in laboratories in a matter of days compared to the billion or so years it has taken natural diamonds to be formed deep in the earth.

De Beers is offering specialised machines to the diamond industry to weed out man-made diamonds, which are far cheaper to produce than the natural ones.

The disdain with which De Beers regards synthetic stones entering the jewellery sector is clear. These diamonds have been used in technical applications such as lasers, but increasingly they are finding their way from China and India into the polished diamond market, completely indistinguishable from natural diamonds.

In a note, "Undisclosed Synthetics. What you need to know", De Beers defines a natural diamond as a "natural mineral consisting essentially of pure carbon crystallised with a cubic structure in the isometric system".

It tells its 81 hand-picked clients called sightholders that not disclosing synthetic diamonds or misrepresenting them as the natural article could cause "irreparable" reputational damage.

"Never use the word ‘diamond’ to describe or identify any object or product not meeting the definition," it warns.

The problem for De Beers is that the diamond pipeline is long and a lot of people are involved, making such an edict practically impossible to enforce.

Martin Rapaport, chairman of diamond services company Rapaport Group, said synthetic diamonds were here to stay and the market and producers had best find ways of coping. "If new products or technologies are more profitable or efficient, they dominate — markets are Darwinian. "They are about survival of the fittest and by the fittest."

Ironically, De Beers has a division called Element Six, which has been producing laboratory-grown diamonds. Element Six makes synthetic diamonds for a host of applications including precision machining, electronics and even bearings.