Lunette — The Crescent Side Stone
Lunette — The Crescent Side Stone
A French term for the half-moon cut that flanks emerald-cut and cushion centres
Lunette is the French term for a half-moon or crescent-shaped gemstone, most often step-cut and used as a side stone flanking a central gem in three-stone rings, pendants, and earring designs. The shape — a flat or slightly curved straight edge paired with a convex outer arc — is one of the standard fancy-cut side-stone forms in the cutter's repertoire, alongside trapezoids, tapered baguettes, kites, and shields. Lunettes appear most frequently in Art Deco jewellery and in contemporary high jewellery where geometric crispness and architectural three-stone composition are part of the design language.
Cutting style and yield
Most lunettes are step-cut, with rectangular facets running parallel to the straight edge of the crescent. The step-cut treatment maintains the geometric clarity of the shape and matches the visual character of the emerald-cut and Asscher centre stones with which lunettes are most often paired. Brilliant-faceted lunettes do exist, particularly in modern productions where added scintillation in the side stones is sought, but step-cuts remain the historic and aesthetic default.
From a yield perspective, the lunette is a useful cut for working irregularly shaped rough that would not yield economically as a more conventional cut. The crescent allows the cutter to work around inclusions, edges of cleavage, or off-axis crystal habit while producing a finished stone that has a defined trade niche. This is one of the structural reasons lunettes are more common in coloured-stone work than in diamond, where the rough is more often economically directed toward more conventional shapes.
Use in jewellery
The lunette's classic application is as a pair of matched side stones flanking an emerald-cut diamond or coloured stone in a three-stone ring. The straight edges of the lunettes meet the straight edges of the centre stone, producing a crisp visual continuity along the finger. The convex outer arcs taper the overall composition and finish the line of the ring.
Beyond the three-stone ring, lunettes appear in tennis bracelets and necklaces alternating with round or rectangular gems, in earring designs as drops or jackets, and in larger high-jewellery pieces as transitional elements between geometric centres. Cartier, Van Cleef & Arpels, and Harry Winston all maintain inventories of matched lunette parcels for bespoke and high-jewellery work.
Matching considerations
Side-stone work depends on accurate matching of weight, dimensions, colour, and clarity. For lunettes, the additional matching dimension is curvature — the radius of the outer arc must be consistent across the pair so that the finished setting has visual symmetry. A lunette pair with even a small mismatch in arc radius will read as imbalanced in the final piece, particularly under the close inspection that fine jewellery commands.
Colour matching for coloured-stone lunettes is the more demanding constraint. Pairing two sapphires, two emeralds, or two rubies of identical colour in the lunette format requires either cutting from the same parcel of rough or sourcing from a deep inventory of pre-cut matched pairs. Diamond lunettes can be matched from broader supply but still require attention to colour grade, clarity character, and cut proportion.
In the trade
Trade vocabulary for crescent side stones varies across cutting centres. Lunette is the formal French term and remains the preferred designation in European high jewellery and at Geneva auctions. American and trade English usage often substitutes "half-moon," while Indian and Thai cutting centres may simply describe the cut by its geometry. Buyers should verify which term a given supplier means by "half-moon" — some use it specifically for stones with a convex outer arc and a flat straight edge, while others apply it more loosely to any roughly crescent-shaped fancy.
Pricing for lunettes follows the broader fancy-shape pricing logic: matched pairs of larger lunettes command a premium over equivalent loose stones because of the matching investment, and well-cut lunettes in fine colour can be the most expensive element of a high-jewellery commission once side-stone weight is significant.