De Beers Adapts Rare Cabochon Cut for Diamonds

(IDEX Online) - De Beers London has adapted the traditional cabochon - one of the rarest cuts for a diamond - to create stones with smooth, rounded profiles resembling water droplets.

The stones produce a softer, more luminous appearance than conventional, faceted diamonds, with light reflected from the smooth surface and  with no facets to conceal inclusions.

De Beers, which spent five years develop the new cutting technique, says fewer than 0.5 percent of diamonds meet the color and clarity requirements, and have a suitable crystal structure, symmetry and other characteristics.

The stones are being introduced in the company's Vibrations high-jewelry collection.

Cabochon is an established, facet-free gemstone-cutting style, most commonly associated with colored stones such as sapphires, rubies and emeralds.

A traditional simple cabochon has a rounded, polished top and a flat bottom, usually in an oval or elliptical shape.

De Beers' version retains the defining facet-free construction of a cabochon but gives the stone a deliberately rounded, water-droplet-like profile.

The company says it developed a specialized precision technique to produce the smooth, domed form in diamond while preserving the character of each stone.

De Beers has not invented the facet-free cabochon, nor is the cabochon new to diamonds. It is adapting an established but very rarely used diamond treatment and developing a particular profile and production process for it.

Cabochon cutting is uncommon in diamond because of the material's exceptional hardness.

The Gemological Institute of America has previously documented natural diamond cabochons, including two stones weighing about 6.29 and 6.07 carats. GIA described cabochon cutting as popular in colored stones but rarely attempted with diamond.

The absence of facets also creates a different quality challenge. Facets can influence the way light travels through a diamond and can reduce the visibility of some inclusions.

A smooth cabochon surface puts the stone's internal characteristics much more fully on display. De Beers says this means the diamonds must have exceptional quality and purity, as well as suitable crystal structure and symmetry.

The result is visually very different from a conventional brilliant-cut diamond. Instead of the sharp flashes produced by numerous angled facets, the De Beers stones have what the company describes as a deep, luminous glow.

The cabochons appear in the Undulation suite of the Vibrations collection, inspired by the Okavango Delta in Botswana. Their rounded forms are intended to suggest water droplets along the river's edge.

Pic courtesy De Beers.