A to Z
Glossary
Every trade has a language. This is the jewelry one, translated: the terms you will hear on a sales floor, read on a certificate or find stamped inside a ring.
- Akoya
- Saltwater cultured pearl from Japan and China, 6 to 9 mm, white or cream with sharp lustre; the classic strand pearl.
- Alloy
- A mix of metals. Gold is alloyed with copper, silver, zinc, palladium or nickel to make it hard enough to wear and to change its colour.
- Appraisal
- A written opinion of value, usually replacement value for insurance. Not a laboratory report and not an offer to buy.
- Assay
- Testing metal to determine its purity. Assay offices in hallmarking countries stamp verified pieces.
- Baguette
- A small, rectangular step-cut stone, usually a diamond, used as an accent beside a centre stone.
- Bezel
- A setting in which a rim of metal surrounds the stone, protecting its edges. The most secure setting for daily wear.
- Brilliant cut
- The faceting style designed for maximum light return, most commonly the 58-facet round brilliant.
- Cabochon
- A stone polished into a smooth dome without facets, used for opal, moonstone, turquoise and star stones.
- Carat
- A unit of weight for gemstones: one fifth of a gram. Not to be confused with karat, the purity of gold.
- Certificate
- Trade shorthand for a gemological laboratory report (GIA, IGI, HRD and others) describing a stone’s characteristics. It states no value.
- Chronometer
- A mechanical watch movement certified for accuracy by an official body such as COSC, typically within minus four to plus six seconds per day.
- Clarity
- The degree to which a stone is free of inclusions and blemishes, graded for diamonds from Flawless to Included (I3).
- Cleavage
- A tendency to split along a crystal plane when struck. Diamond, topaz and kunzite have it; sapphire does not.
- Colour change
- A shift in a stone’s colour between daylight and incandescent light, most famously in alexandrite.
- Corundum
- The mineral that forms ruby (red) and sapphire (every other colour). Hardness 9.
- Cultured pearl
- A pearl grown in a mollusc after a bead or piece of tissue is inserted by hand. Almost all pearls sold today.
- Cushion cut
- A square or rectangular shape with rounded corners and a soft, pillow-like sparkle.
- Depreciation
- The loss in value between the retail price of a piece and what a buyer will pay for it. For ordinary jewelry, often more than half at the door.
- Diffusion
- A treatment that introduces colour-causing elements into the surface of a sapphire at high temperature. Must be disclosed; lowers value sharply.
- Eye-clean
- A stone whose inclusions cannot be seen with the naked eye. The practical clarity standard for most buyers.
- Facet
- A flat, polished surface on a cut gemstone. Their angles and proportions decide how the stone handles light.
- Fineness
- Gold or silver purity in parts per thousand: 750 is 18K, 925 is sterling silver.
- Fire
- The flashes of spectral colour a diamond shows as it splits white light; a product of cut.
- Fluorescence
- A glow, usually blue, that some diamonds show under ultraviolet light. Noted on reports; medium and strong fluorescence are discounted.
- Full set
- A pre-owned watch sold with its original box, papers, tags and links. Adds value and shortens the sale.
- GIA
- Gemological Institute of America, the laboratory whose diamond grading system and reports are the industry reference.
- Girdle
- The thin outer edge of a cut stone, where the crown meets the pavilion. Report numbers are often laser-inscribed there.
- Hallmark
- An official mark struck by an independent assay office guaranteeing the purity of a precious metal. Distinct from a maker’s stamp.
- Halo
- A ring of small stones surrounding a centre stone, making it look larger and adding sparkle.
- HPHT and CVD
- The two methods of growing diamonds in a laboratory: high pressure and high temperature, and chemical vapour deposition.
- IGI
- International Gemological Institute, a laboratory that grades most lab-grown diamonds and many natural ones.
- In-house movement
- A watch movement designed and made by the brand itself rather than bought from a specialist supplier.
- Inclusion
- A crystal, feather, cloud or other internal feature in a gemstone. Graded for diamonds; expected in emeralds.
- Karat
- Gold purity in twenty-fourths: 24K is pure gold, 18K is 75 percent, 14K is 58.5 percent.
- Lab-grown
- A diamond or other stone crystallised in a laboratory. Chemically identical to the mined version, priced far lower, with a thin resale market.
- Lustre
- The quality and sharpness of light reflected from a pearl’s surface; the first thing a pearl is judged on.
- Melee
- Small diamonds, usually under 0.2 carats, used in pavé and halo settings. Worth little on resale.
- Millegrain
- A decorative edge of tiny beads of metal, typical of Edwardian and Art Deco jewelry.
- Mohs scale
- A ranking of scratch hardness from 1 (talc) to 10 (diamond). Anything under 7 is scratched by household dust.
- Nacre
- The layered material a mollusc lays down to form a pearl. Thicker nacre means longer-lasting lustre.
- Old-cut
- Diamond cuts from before the twentieth century, such as old-mine and old-European cuts, with small tables and high crowns. Prized for their candlelight sparkle.
- Origin
- The geographic source of a gemstone, determined by a laboratory from inclusions and chemistry. Famous origins carry premiums.
- Padparadscha
- A rare pink-orange sapphire, named after the Sinhalese word for lotus blossom.
- Pavé
- A setting style in which small stones are set close together, covering the metal like paving.
- Pennyweight
- An old unit of weight still used by some gold buyers: 1.555 grams. Ask for prices per gram instead.
- Pigeon’s blood
- The trade name for the finest ruby colour: vivid, pure red with a hint of blue.
- Platinum 950
- The standard platinum alloy for jewelry: 95 percent platinum, naturally white and hypoallergenic.
- Prong
- A metal claw holding a stone in a setting. Six prongs hold more securely than four; worn prong tips are re-tipped by a jeweler.
- Provenance
- The documented ownership and origin history of a piece. For signed and antique jewelry, a large part of its value.
- Rhodium
- A bright white platinum-group metal used to plate white gold. Wears off within a few years and is re-applied.
- Rose cut
- An old diamond cut with a flat base and a domed, faceted top, popular from the sixteenth to nineteenth century and revived in modern design.
- Rough
- An uncut gemstone crystal as mined.
- Scintillation
- The sparkle a stone shows as it or the light moves; the pattern of light and dark flashes.
- Signed piece
- Jewelry stamped with the name of a recognised house such as Cartier or Van Cleef & Arpels. Signed pieces sell for far more than their materials.
- Solitaire
- A ring with a single stone. The classic engagement ring form.
- Spot price
- The current market price of a precious metal per troy ounce, quoted continuously during trading hours. Shown live on this site.
- Spread
- The difference between a dealer’s buying and selling price for the same product; the real cost of trading gold. Also, the visible diameter of a stone relative to its weight.
- Step cut
- A faceting style with long, parallel facets in steps, as in emerald and Asscher cuts. Produces flashes rather than sparkle.
- Sterling silver
- Silver alloyed to 92.5 percent purity, stamped 925.
- Synthetic
- A stone made by humans with the same chemistry and structure as the natural mineral. Not the same as an imitation, which only looks alike.
- Table
- The large flat facet on top of a cut stone. Its size relative to the stone’s width is a key proportion.
- Tourbillon
- A watch complication in which the escapement rotates in a cage to average out the effect of gravity. Expensive and mostly decorative today.
- Treatment
- Any process that alters a gemstone’s appearance after mining: heating, oiling, irradiation, diffusion, dyeing. Accepted when disclosed.
- Troy ounce
- The unit for precious metals: 31.1035 grams, heavier than the ordinary ounce.
- Vermeil
- Gold plating over sterling silver. Not solid gold and without meaningful metal value.
- VVS, VS, SI
- Diamond clarity grades: very very slightly included, very slightly included, slightly included. Each in two steps (1 and 2).
- White gold
- Gold alloyed with palladium or nickel to look white, usually rhodium-plated. Contains as much gold as yellow gold of the same karat.
- Window
- A pale, see-through area in the centre of a coloured stone caused by a shallow cut. Reduces beauty and value.
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Now use the vocabulary
Twenty-four guides and seven tools that put these words to work.