Jewellery Glossary
A–Z reference for jewellery, gemstone, and manufacturing terms. Search or browse by letter.
56 terms total
A
Alloy
A mixture of a precious metal with other metals to improve durability, alter colour, or reduce cost. 18K gold, for example, is an alloy of pure gold with copper, silver, and/or palladium.
Assay Office
An official body that tests and certifies the purity of precious metals. See our Hallmarks Guide for UK assay office marks.
B
Baguette Cut
A rectangular step-cut typically used for small accent stones, often set in a row via channel setting.
Bail
The small loop or fitting at the top of a pendant through which a chain passes.
Basket Setting
A style of prong setting where the prongs form an open, basket-like structure beneath the stone, allowing maximum light entry from below.
Bezel
A setting style where a thin rim of metal wraps entirely around a stone's girdle. See our full Setting Types Guide.
Bezel (Diamond Anatomy)(Not to be confused with the bezel setting)
In diamond anatomy, the eight kite-shaped facets on the crown of a round brilliant, between the table and the girdle (also called kite facets).
Blemish
A surface characteristic on a gemstone (as opposed to an internal inclusion), such as a scratch, nick, or polish line.
Brilliance
The overall brightness of a gemstone created by light reflecting off internal and external facets.
C
Cabochon
A gemstone cut and polished into a smooth, rounded shape rather than faceted. Common for opal, moonstone, and star sapphires.
Calibrated Stone
A gemstone cut to a precise, standard millimetre size to fit commercially available mountings. See our Gemstone Size Chart.
Carat (ct)(not karat)
The unit of weight for gemstones, equal to 200 milligrams. Not to be confused with karat (gold purity).
Cathedral Setting
A setting style where arching bands of metal rise from the shank to elevate the centre stone. See our Setting Types Guide.
Channel Setting
Stones set in a row between two parallel metal walls, with no visible prongs. See our Setting Types Guide.
Clarity
A measure of the presence of internal inclusions and external blemishes in a gemstone. See our Clarity & Grading Guide.
Cluster Setting
Multiple small stones grouped tightly to create the visual impression of one larger stone. See our Setting Types Guide.
Colour Grade
A measure of how colourless a diamond is, graded D (colourless) through Z (light yellow/brown). See our Clarity & Grading Guide.
Crown
The upper portion of a faceted gemstone, above the girdle.
Culet
The small facet (or point) at the very bottom of a gemstone's pavilion.
Cut Grade
A measure of how well a diamond's proportions and facets interact with light. See our Clarity & Grading Guide.
D
Depth Percentage
The height of a diamond from table to culet, expressed as a percentage of its width — a key factor in how well the stone reflects light.
Diffusion Treatment
A gemstone treatment where colour-inducing elements are diffused into the surface layer under extreme heat. See our Clarity & Grading Guide.
E
Eye-Clean
A gemstone with no inclusions visible to the naked eye, even though inclusions may be present under magnification.
F
Facet
A flat, polished surface on a cut gemstone. The number and arrangement of facets significantly affects brilliance.
Fancy Cut
Any diamond or gemstone shape other than round brilliant — includes oval, pear, marquise, cushion, and others. See our Diamond Shapes Chart.
Fineness
The purity of a precious metal expressed in parts per thousand, e.g. 925 for sterling silver. See our Hallmarks Guide.
Flush Setting
A setting where the stone sits level with the metal surface, with no raised prongs or bezel. Also called gypsy setting. See our Setting Types Guide.
G
Girdle
The narrow band around the widest part of a gemstone, separating the crown from the pavilion.
Gold Vermeil
Sterling silver with a substantial layer (minimum 2.5 microns) of gold plating. See our Hallmarks Guide.
Gold-Filled
A layer of karat gold mechanically bonded to a base metal, making up at least 1/20 of the item's weight. See our Hallmarks Guide.
H
Hallmark
A stamped mark indicating a precious metal's purity, and in the UK, the assay office and year of testing. See our full Hallmarks Guide.
Halo Setting
A centre stone surrounded by a circle of smaller pavé-set stones. See our Setting Types Guide.
Heat Treatment
Controlled heating of a gemstone to improve colour or clarity, common in ruby and sapphire. See our Clarity & Grading Guide.
I
Inclusion
An internal characteristic within a gemstone, such as a crystal, feather, or cloud, formed during the stone's natural growth.
K
Karat (K)(not carat)
The unit of gold purity out of 24 parts, e.g. 18K = 75% pure gold. Not to be confused with carat (gemstone weight).
L
Lab-Grown
A gemstone grown in a controlled laboratory environment, chemically and physically identical to its natural counterpart.
M
Marquise Cut
An elongated, boat-shaped diamond or gemstone cut with pointed ends. See our Diamond Shapes Chart.
Melee
Small diamonds or gemstones, generally under 0.20 carats, used as accent stones in pavé, halo, or channel settings.
Millesimal Fineness
A system expressing metal purity in parts per thousand, e.g. 750 for 18K gold. See our Hallmarks Guide.
O
Oiling
Filling surface-reaching fractures in a gemstone (most commonly emerald) with oil or resin to improve apparent clarity. See our Clarity & Grading Guide.
P
Pavilion
The lower portion of a faceted gemstone, below the girdle, which reflects light back up through the crown.
Pavé
Small stones set closely together across a surface, held by tiny beads or prongs, creating a continuous "paved" sparkle. See our Setting Types Guide.
Plating
A thin layer of metal (often gold) electrochemically applied over a base metal. See our Hallmarks Guide.
Plumb Gold
Gold marked with a "P" suffix (e.g. 10KP) confirming its purity is exact rather than rounded. See our Hallmarks Guide.
Prong
A metal claw that grips a gemstone to hold it in place, typically 4 or 6 per setting. See our Setting Types Guide.
R
Rhodium Plating
A thin plating of rhodium (a platinum group metal) applied over white gold to enhance its bright white colour and add scratch resistance.
Rolled Gold Plate (RGP)
A karat-gold sheet mechanically bonded and rolled onto base metal, containing less gold than gold-filled but more than standard plating. See our Hallmarks Guide.
S
Setting
The structure that holds a gemstone in place within a piece of jewellery. See our full Setting Types Guide.
Shank
The band portion of a ring that wraps around the finger.
Sterling Silver
An alloy of 92.5% pure silver and 7.5% other metals (usually copper), stamped 925. See our Hallmarks Guide.
T
Table
The large, flat top facet of a faceted gemstone.
Tension Setting
A setting where the stone appears to float, held only by the spring-like pressure of the band itself. See our Setting Types Guide.
Treatment
Any process applied to a gemstone to enhance its colour, clarity, or durability. See our full treatment guide.
Type I/II/III (Gemstone Clarity)
A classification system for coloured gemstone clarity based on how commonly each species forms with inclusions. See our Clarity & Grading Guide.
V
Vermeil
See Gold Vermeil.
VS / VVS / SI / I
Clarity grade abbreviations (Very Slightly Included, Very Very Slightly Included, Slightly Included, Included). See our Clarity & Grading Guide.
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Why This Glossary Exists
The jewellery trade uses hundreds of specific technical terms that rarely appear in everyday language — from settings and cuts to metal fineness and gemstone treatments. Whether you're a brand owner sourcing manufacturing, a retailer training staff, or a shopper trying to understand a product description, this glossary breaks down the terminology in plain English.
Related Resources
For deeper coverage of specific topics referenced here, see our Hallmarks & Metal Stamps Guide, Jewellery Setting Types Guide, Gemstone Clarity & Grading Guide, Diamond Shapes & Size Chart, and Gemstone Size & Weight Chart.
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If there's a term you'd like added to this glossary, or a definition you think needs clarifying, we'd love to hear from you.
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