A collet setting is a method of securing a gemstone within a continuous metal collar — the collet — that encircles the girdle and is burnished or pressed inward over the stone's edge to hold it in place. The term is the standard British designation for what American usage more commonly calls a bezel setting, though in precise historical and trade contexts the two are not entirely synonymous: a collet traditionally implies a closed-back construction, in which the base of the metal cup is sealed rather than open. This distinction matters both technically and historically, as the closed back was integral to pre-electric-lighting jewellery practice.

Construction and Technique

The collet itself is fabricated from a strip of metal — gold, silver, or platinum — formed into a band whose diameter matches the girdle of the intended stone. The strip is soldered into a ring, fitted with a base plate to close the back, and then seated onto the mount. Once the stone is placed, the upper edge of the collar is worked with a burnisher or pusher, folding the metal evenly over the girdle and, where the stone's crown permits, slightly onto the bezel facets or cabochon shoulder. The result is a continuous, uninterrupted band of metal that protects the entire circumference of the girdle — a particular advantage for stones prone to chipping, such as emerald, opal, or antique rose-cut diamonds whose thin girdles are vulnerable to impact.

In closed-back collets, the sealed base serves a further purpose: it creates a chamber behind the stone into which foil could be inserted. Gold, silver, or coloured foil placed beneath a pale or included stone amplified its apparent colour and brilliance under candlelight, a technique ubiquitous in Georgian jewellery before the advent of modern cutting and lighting. Foiled collets are encountered regularly in eighteenth- and early nineteenth-century pieces set with paste, chrysoberyl, topaz, and early brilliant-cut diamonds.

Historical Context

The collet setting dominated European fine jewellery from at least the Renaissance through the mid-Victorian period. Georgian parures — suites of necklace, earrings, brooch, and bracelet — relied almost exclusively on closed-back collets, often in silver over gold (argent sur or), to maximise the reflective effect of foil-backed stones. As gas lighting and later electric light rendered foiling unnecessary, and as improved cutting techniques produced stones of greater intrinsic brilliance, the open-back bezel and the prong (claw) setting gradually supplanted the closed collet for faceted stones. Nevertheless, the collet remained the preferred setting for cameos, intaglios, and cabochon-cut gems throughout the Victorian period, and the term persisted in British jewellery trade education and hallmarking documentation.

Collet versus Bezel: A Terminological Note

In contemporary British gemmological and trade usage, collet and bezel are often used interchangeably, and both the Gemmological Association of Great Britain and the National Association of Goldsmiths have historically employed both terms. The practical distinction — closed back versus open back — is more consistently observed in antique jewellery scholarship and auction-house cataloguing than in modern workshop parlance. When examining a piece described as a collet setting, it is worth confirming whether the back is sealed, as this affects both the historical dating of the piece and the advisability of ultrasonic or steam cleaning, which can loosen or discolour foil linings.

Contemporary Use

Modern jewellers continue to employ collet-style settings, typically in their open-back bezel form, for cabochon-cut stones, antique-style commissions, and any gem where girdle protection is a priority. Platinum and white gold collets are standard for contemporary work; yellow gold remains preferred for period reproductions. The setting suits a wide range of stone shapes — round, oval, cushion, and freeform — and is particularly favoured for opals, turquoise, and other materials whose surface finish would be marred by prong pressure. For fragile antique stones being remodelled or remounted, a well-fitted collet is often the most conservative and protective choice available.

Further Reading

• GIA: Gemstone Setting Styles Overview