Guide to gem cuts

Every cut has a reason to exist

A gem's cut is never a purely aesthetic choice: it answers optical constraints, the stone's fragility, the shape of the rough, and the colour one wishes to bring out. Our eight illustrated cards show the classic cuts from above, with their facets.

The faceted cuts

The round brilliant is the culmination of three centuries of optical research: its 57 facets (58 with the culet) are calculated to maximise the return of light to the eye. It is the cut that produces the most fire — and the timeless choice for engagement rings.

The princess cut, square with sharp corners, offers a very modern brilliance but fragile angles: it is protected by a setting that covers the corners.

The emerald cut is a “step” cut: its parallel rectangular facets create an effect of successive mirrors that reveals clarity rather than fire. It was not invented by chance — emerald is a fragile, often included stone, and this cut with its bevelled corners reduces the risk of chipping while embracing the inclusions.

The cushion, with its softened corners, has a vintage charm much prized for sapphires and antique diamonds. The oval has an advantage well known to shrewd buyers: weight for weight it looks larger than a round, and elegantly lengthens the finger.

The pear, between brilliant and marquise, is worn point towards the fingernail — that point is its fragile zone. The marquise (or navette), with its two tapered ends, was born — so legend says — of the smile of the Marquise de Pompadour, whose shape Louis XV is said to have wished to immortalise.

The cabochon: when facets would be a mistake

The cabochon — a smooth polished dome with no facets — is not a “lesser” cut. It is the only possible cut for opaque stones (turquoise, lapis, malachite) and above all for those showing optical effects: the asterism of a star sapphire and the chatoyancy of tiger's eye appear only on a domed surface. A faceted cut would simply destroy them.