Part of The Grand Glossary: A Collector's Reference. This section covers the specialist vocabulary of antique and period jewellery, from gemstone identification and cutting terminology to metalworking techniques, enamelling traditions, hallmarking, and the vocabulary of period styles. Terms are arranged alphabetically within thematic groupings.
Gemstones: Identification and Properties
Cabochon
A gemstone that has been shaped and polished to a smooth, convex dome rather than faceted. The cabochon cut predates faceted cutting and remains in use for opaque and translucent stones — turquoise, coral, lapis lazuli, malachite, moonstone, star sapphire, and cat’s eye chrysoberyl — where the optical effect of the stone’s interior (asterism or chatoyancy) is displayed to better advantage without faceting. High-domed cabochons are described as high-cabochon or baroquet; flat-based cabochons cut to a dome on top and flat beneath are the standard form.
Chatoyancy
An optical effect in certain gemstones — most notably cat’s eye chrysoberyl, but also tiger’s eye, alexandrite, and some tourmalines and beryls — in which a band of light appears to move across the surface of a cabochon-cut stone, resembling the slit pupil of a cat’s eye. The effect is produced by the reflection of light from parallel fibrous inclusions or hollow tubes within the stone. The sharpness and centring of the cat’s eye band, and the colour and translucency of the stone, are the primary quality factors. Chrysoberyl cat’s eye is the finest variety; other chatoyant stones are designated by their mineral name (sillimanite cat’s eye, tourmaline cat’s eye).
Doublet
A composite stone consisting of two parts cemented together to simulate a more valuable gem. A common form is the garnet-topped doublet, in which a thin slice of red garnet is cemented to a glass base; the garnet top provides hardness and natural lustre, while the glass base provides colour. Doublets were widely used as simulants in 18th and 19th-century jewellery and are identified by their flat, regular junction line when viewed from the side, and by the visible difference in lustre between the top and the base. Doublets set in closed settings are particularly difficult to identify without removal.
Foiling
The backing of a gemstone or paste with a thin sheet of metallic foil — gold, silver, or coloured metal — to enhance or alter its colour and brilliance. Foiling was standard practice for paste jewellery of the 18th century and was used for natural stones in closed settings. A foiled stone set in a closed-back setting cannot be examined from behind without dismounting; the presence of a closed back should always be noted in descriptions and valuations. Foiling is revealed when stones are examined in transmitted light or removed from their settings.
Inclusion
Any internal feature within a gemstone — a crystal of another mineral, a liquid-filled cavity, a feather (a fracture), a needle (a thin crystal), a cloud (a diffuse group of tiny inclusions), or a fingerprint (a partially healed fracture). Inclusions are the primary tool of the gemmologist in identifying a stone’s natural origin and distinguishing natural stones from synthetics and simulants. In diamond grading, inclusions are assessed for their number, size, position, and nature under 10x magnification to determine the clarity grade. In coloured stones, some inclusions — such as the silk (rutile needles) in sapphires and rubies — may add to the stone’s character and assist in confirming natural origin.
Paste
A highly refractive lead glass used as a simulant for gemstones, produced with great skill in the 18th century by craftsmen including Georges Frédéric Strass of Paris, from whom the term strass derives. Fine 18th-century paste jewellery — particularly English and French pieces — is collected and valued in its own right, not merely as a substitute for gemstone jewellery. Paste stones were cut with the same precision as diamonds, foiled in closed settings to maximise brilliance, and mounted in silver to complement their cool sparkle. Georgian paste of high quality can approach the appearance of fine diamonds; its distinction from genuine gems requires gemmological examination.
Synthetic Gemstones
Gemstones produced in the laboratory with the same chemical composition and crystal structure as their natural counterparts, as opposed to simulants (which merely resemble the natural stone). The principal synthetic gemstones in the market are synthetic ruby and sapphire (produced by the Verneuil flame-fusion process from 1902), synthetic emerald (hydrothermal growth), synthetic spinel, and synthetic diamond (HPHT and CVD processes). The distinction between natural and synthetic is of fundamental commercial importance and requires gemmological testing; synthetic stones of high quality can be visually identical to natural ones. The presence of a laboratory report from a recognised gemmological laboratory (GIA, Gübelin, SSEF) is important for significant coloured stones.
Gemstone Cuts
Briolette
A teardrop-shaped stone cut entirely with triangular or rectangular facets, with no flat table, designed to be drilled and suspended as a pendant or drop. Briolette-cut diamonds were fashionable in the 18th century and have enjoyed periodic revivals. The quality of the briolette depends on the evenness and precision of the facets and the symmetry of the drop form.
Brilliant Cut
The standard modern cut for round diamonds and other transparent gemstones, comprising 57 or 58 facets arranged in a specific pattern designed to maximise the return of light through the crown of the stone. The modern round brilliant cut was developed by Marcel Tolkowsky in 1919 on the basis of mathematical analysis of ideal proportions. Earlier brilliant cuts — the old mine cut (cushion-shaped, with a high crown and small table, characteristic of the 18th and early 19th centuries) and the old European cut (rounder, with a very small table and high crown, characteristic of the late 19th and early 20th centuries) — are distinct from the modern brilliant and are valued by many collectors for their different optical character.
Rose Cut
A gemstone cut consisting of a flat base and a domed upper surface covered with triangular facets meeting at a point, resembling the unfolding petals of a rosebud. The rose cut was developed in the 16th century and was the dominant cut for diamonds from the 17th century until the development of the brilliant cut in the late 17th and early 18th centuries. It continued in use for smaller stones throughout the 18th and 19th centuries. Rose-cut diamonds have a soft, gentle sparkle quite different from the brilliance of a modern cut and are widely used in antique jewellery reproduction and in contemporary design.
Table Cut
One of the earliest faceted cuts for diamonds, in which the natural octahedral crystal is ground to produce a large flat table facet on the top and a smaller culet facet on the bottom, with four large facets on the crown and four on the pavilion. The table cut was the dominant diamond cut from the 15th to the 17th centuries and is found in Renaissance and early Baroque jewellery. Its simple form and the large, flat table facet give table-cut diamonds a distinctive, architectural appearance.
Settings and Mounts
Bezel Setting
A setting in which a stone is held by a continuous collar of metal that encircles it and is pressed or burnished over the stone’s girdle to secure it. The bezel setting protects the stone’s edge and is particularly appropriate for cabochons and softer stones. In antique jewellery, closed-back bezel settings with foiled stones were standard until the late 18th century; open-back bezels, which allow light to pass through the stone, became more common as cutting improved.
Collet
A cylindrical or tapering metal cup in which a gemstone is set, the metal being burnished over the stone’s edge to hold it. The collet is the basic form of the bezel setting. In earlier jewellery, collets were typically made of gold or silver sheet; later collets may be cut-down (with the upper edge scalloped or shaped) to expose more of the stone. The quality of the collet work is an indicator of the standard of the mount.
En Tremblant
A jewellery mounting technique in which an element — typically a flower, butterfly, or other naturalistic form set with diamonds or other gemstones — is mounted on a fine spring so that it trembles with the wearer’s movement, creating a constantly shifting play of light. En tremblant pieces were fashionable from the mid-18th century and are particularly associated with French jewellery of the Louis XV period and with the naturalistic floral jewellery of the 19th century. The condition of the spring mechanism and the security of the set stones are the primary assessment criteria.
Pavé Setting
A setting technique in which small stones — typically diamonds — are set closely together in a surface so that the metal beneath is largely or entirely concealed, creating the impression of a continuous surface of stone. Pavé (French for paved) setting requires great skill to execute well; the beads of metal that hold each stone must be raised and rounded cleanly, and the stones must be level and evenly spaced. The technique was widely used in the late 19th and early 20th centuries and remains standard in contemporary jewellery.
Prong (Claw) Setting
A setting in which a stone is held by a series of thin metal prongs (claws) that grip its girdle, leaving the maximum area of the stone exposed to light. The prong setting was developed in the 19th century and became the standard for solitaire diamond rings following the introduction of the Tiffany setting (six prongs, raised on a plain shank) in 1886. Earlier jewellery typically used collet, bezel, or closed settings; the prong setting reflects the increasing emphasis on the brilliance of the cut stone rather than the decorative quality of the mount.
Enamelling Techniques
Champlevé
An enamelling technique in which recesses are cut, etched, or cast into a metal base — typically copper, bronze, or gold — and filled with enamel paste, which is then fired and ground flush with the surrounding metal surface. The metal between the recesses forms the design outline and remains visible. Champlevé was the dominant enamelling technique in medieval European metalwork, associated particularly with the workshops of the Meuse valley and of Limoges. It was widely used for ecclesiastical metalwork, reliquaries, and secular objects. Victorian champlevé on copper and brass is a distinct and collected category.
Cloisonné
An enamelling technique in which thin metal wires (cloisons) are soldered or fused to a metal base to form the outlines of the design, creating cells that are filled with enamel paste and fired. The wire outlines remain visible in the finished piece, defining the design. Cloisonné is the dominant enamelling tradition of China, Japan, and the Byzantine world, and was used in medieval European jewellery. It is distinguished from champlevé by the addition of wires rather than the removal of metal to create the cells.
Guilloché
An engine-turned engraved pattern cut into a metal surface, over which a transparent or translucent enamel is applied to create a shifting, luminous effect as the light catches the engraved pattern beneath. Guilloché enamel is associated above all with the work of the House of Fabergé, which brought the technique to a peak of refinement in the imperial Easter eggs and the range of small decorative objects produced for the Russian and European aristocracy. The quality of the guilloché is assessed by the precision and regularity of the engraved pattern; the enamel is assessed for its depth, evenness, and freedom from bubbles or surface damage.
Limoges Enamel
Painted enamel on copper produced in Limoges, France, from the 12th century onwards. Medieval Limoges champlevé enamel was produced on an industrial scale for ecclesiastical metalwork across Europe. From the late 15th century, Limoges workshops developed grisaille enamel (painting in grey and white on a black ground to simulate the effect of carved stone or relief) and polychrome painted enamel on copper. Renaissance Limoges painted enamels — by craftsmen including Léonard Limosin, Pierre Reymond, and the Penicaud family — are among the most prized objects of the applied arts.
Plique-à-Jour
An enamelling technique in which enamel is suspended in a metal framework without any backing, so that light passes through the translucent enamel cells, creating an effect resembling stained glass or a butterfly’s wing. The technique requires great skill: the enamel must be built up in thin layers, typically on a temporary copper backing that is subsequently dissolved away, leaving the self-supporting enamel within its wire framework. Plique-à-jour is associated with Art Nouveau jewellery — particularly the work of René Lalique and the Norwegian silversmith David-Andersen — and is one of the most technically demanding of all enamelling techniques. The fragility of the finished piece requires careful handling and storage.
Period Styles
Georgian (c.1714–1837)
Jewellery of the Georgian period is characterised by fine craftsmanship in gold and silver, a predominance of paste, foiled stones, and natural organic materials (coral, ivory, tortoiseshell, hair, and seed pearls), and a succession of stylistic fashions from the rococo curves of the mid-18th century through the neoclassical severity of the Adam period to the archaeological and sentimental styles of the Regency. Hallmarking of gold jewellery was not consistent in Britain until 1798; much Georgian jewellery is unmarked or bears only partial marks. Mourning jewellery — incorporating hair, jet, and black enamel — is a distinct and important subcategory.
Victorian (1837–1901)
Victorian jewellery encompasses an enormous range of styles and materials, from the archaeological revival work of Castellani and the Giuliano family (inspired by Etruscan and classical antiquity) to the sentimental language-of-flowers and forget-me-not pieces of the mid-Victorian period, the mourning jewellery that proliferated after the death of Prince Albert in 1861, and the naturalistic diamond and pearl jewellery of the late Victorian era. The period saw the industrialisation of jewellery production, the introduction of electrogilding, and the use of new materials including vulcanite, aluminium (briefly fashionable in the 1850s–60s), and Scottish pebble and granite.
Arts and Crafts (c.1880–1910)
Jewellery of the Arts and Crafts movement was made in conscious reaction against industrial production, emphasising handcraftsmanship, natural materials, and the intrinsic qualities of the maker’s hand. British Arts and Crafts jewellery — associated with makers including C.R. Ashbee, the Guild of Handicraft, Liberty and Co., and Gaskin — typically features hammer-finished silver or gold set with semi-precious stones (turquoise, amethyst, moonstone, chrysoprase, and blister pearls) in organic, flowing designs. Enamelling in the Arts and Crafts tradition uses plique-à-jour and champlevé as expressive, painterly techniques rather than purely decorative ones.
Art Nouveau (c.1890–1910)
Art Nouveau jewellery is characterised by organic, flowing forms derived from nature — flowers, insects, female figures with flowing hair, dragonflies, and peacocks — executed with extraordinary technical virtuosity. The French masters of Art Nouveau jewellery, including René Lalique, Georges Fouquet, and Lucien Gaillard, used plique-à-jour enamel, carved horn, ivory, and unusual stones (including opal and moonstone, valued for their translucency and iridescence) alongside diamonds in unconventional settings. Art Nouveau jewellery prioritises the artistic quality of the object over the intrinsic value of its materials.
Edwardian (c.1901–1915)
Edwardian jewellery is characterised by the use of platinum — which became practical for jewellery following the development of the oxyacetylene torch — to create lace-like settings of great delicacy for diamonds and pearls. The Edwardian aesthetic is one of lightness, whiteness, and femininity: garlands, bows, tassels, and floral swags in platinum and white gold set with diamonds and pearls are its most characteristic expressions. The introduction of platinum allowed far finer settings than silver or gold permitted, as platinum is both stronger and more resistant to wear.
Art Deco (c.1920–1939)
Art Deco jewellery is characterised by geometric forms, strong colour contrasts, and the use of platinum, diamonds, and coloured stones — particularly emeralds, rubies, sapphires, and black onyx — in combinations of bold graphic impact. The movement drew on Egyptian, African, and Far Eastern visual sources alongside the abstract geometry of modernist art and architecture. The major Parisian houses — Cartier, Van Cleef and Arpels, Boucheron, and Mauboussin — defined the Art Deco jewellery aesthetic, which was widely disseminated through less expensive commercial production. Signed pieces by the major houses command significant premiums.
Marks, Standards, and Legal Frameworks
Gold Standards and Carat
The purity of gold is expressed in carats (or karats in American usage), representing the number of parts of pure gold per 24 parts of alloy. 24-carat gold is pure gold; 18-carat gold contains 18 parts gold and 6 parts other metals (typically silver and copper); 9-carat gold contains 9 parts gold and 15 parts other metals. In the United Kingdom, 9-carat gold was recognised as a legal standard from 1854 and became the most widely used gold standard for commercial jewellery. Gold articles must be hallmarked with the appropriate carat mark by the assay office before sale.
Platinum Marks
Platinum has been subject to compulsory hallmarking in the United Kingdom since 1975. The standard mark for platinum is 950 (parts per thousand), represented by an orb symbol. Platinum jewellery made before 1975 — the great period of Edwardian and Art Deco fine jewellery — is typically unmarked or marked only with maker’s marks, and its identification as platinum rather than white gold or silver requires testing.
Unmarked Jewellery
Much antique jewellery, particularly of the Georgian period and earlier, is unmarked or partially marked. The compulsory hallmarking of gold jewellery in the UK was not consistently enforced for small articles before the 19th century, and much jewellery was exported before hallmarking or made for personal rather than commercial use. Unmarked jewellery should be tested to establish the metal standard before purchase; X-ray fluorescence (XRF) spectrometry is the standard non-destructive test for precious metal content.
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