GLOSSARY OF USEFUL JEWELLERY TERMS
In this section, we list alphabetically specialist terms which we feel are particularly relevant to our product range and services. If you require any additional information at any time, please contact customer services.
An ancient name for a diamond, derived from the Greek word Adamas, meaning unconquerable.
These come mainly from the seas around Japan and account for the vast majority of cultured pearls on the world market today. They range in size from 2.5 mm - 10 mm, in shape from round to slightly baroque, and though basically white in colour, their overtones include silver, pink, cream, blue / grey and green.
A combination of two or more compatible metals, fused together to form a homogenous metal with new physical attributes better suited to a particular function.
The process for testing the purity of the gold, silver or platinum. On completion, the appropriate hallmark will be applied. Assaying has been a legal requirement in Great Britain since 1300 for articles of silver and gold, and since 1975 for platinum.
A diamond which has been cut into a narrow rectangle. The function of these stones is normally to add decorative detail to a piece of jewellery, rather than to be the focal point.(See 'Tapered Baguette').
A style of setting in which the gemstone is held in place by a fine layer of metal, which just overlaps the girdle to hold it in place. This metal rim can protect the stone from damage without preventing light from entering it.(See 'Rubover Setting').
Describes an imperfection on the surface of gemstone, in particular when referring to pearls.
A pearl which has grown attached to the inner shell of a mollusc, resulting in flat, non-nacreous underside, which is usually obscured when set in jewellery.
A description of the basic underlying colour of a pearl. It is usually complimented by a reference to any 'overtones'.
A small ring-shaped device for fastening a necklace. The partly hollow interior conceals a tongue which can be drawn back by a protruding knob, before springing back into position.
Describes the amount of light reflected back to the viewer from the front of the stone.
A style of cut developed to maximise the amount of light reflected to the eye by a diamond. It generally refers to round diamonds, though may loosely describe the style when the technique is applied to other shapes of stone. It is characterised by having 57 facets, whose relative proportions and angles are governed by strict optical criteria. Sometimes a small 58th facet is be applied by touching the 'culet' (the bottom point of the diamond) to the polishing wheel or 'lathe'.
Term often used to describe the small clips which fasten to the back of earring posts.
A style of cut used for some coloured gemstones, characterised by a flat base and a smooth rounded top, in the form of a dome.
A loose trade description for a diamond which, as the name suggests, has an intense yellow body colour.
Term refers to stones of lower colour grades, which carry a yellowish tinge, without being intense or attractive enough to classify them as 'fancy' colour diamonds. The description stems from the 19th century, when diamonds from the South African Cape tended to be of a distinctly yellowish hue in contrast to the whiter stones from Brazil.
Carat (Ref diamonds):
A unit of measurement for weighing diamonds equal to 1/5th gram. A carat can be subdivided into 4 'grains' and 100 'points'.
Carat (Ref gold):
A term used to describe the relative purity of gold alloys, measured as parts in 24. When 18 parts in 24 are pure gold, the alloy is said to be 18ct, when 9 parts in 24 are pure it is said to be 9ct.
A term used to describe internal the internal purity of a diamond. When examined under x10 magnification the presence and location of 'inclusions' will determine the stone's clarity grade.
A style of setting in which a gemstone is held in place by a series of prongs or claws which overlap its surface.
In spite of a diamond's immense strength, it possesses four plains of atomic weakness. These lie parallel to the octahedral faces of an uncut stone, and are known as 'cleavage faces' . They provide the diamond cutter with one of the two traditional methods for dividing an uncut stone (-refer to 'Saw' for the second). By delivering a sharp blow in a direction parallel to one of these faces, a clean break can be achieved. These plains of weakness are sometimes visible in a cut diamond, when they are referred to as 'grain'.
A style of setting in which the stone is mounted within a collar of metal, the upper edge of which has been bent or 'rubbed' over the edge of stone. Also known as 'rubover' setting.
Colour (Ref. diamond):
The presence and degree of colour is one of the criteria on which a diamond is graded. An internationally accepted system exists for allocating grades, relative to a scale from ranging from D (colourless) to Z (strong off white).
That part of the diamond which lies above the 'girdle' of the stone.
The lowest point on the underside or 'pavilion' of a diamond. Sometimes this has been touched against the polisher's lathe to produce a small culet facet. This was originally done to guard against splintering the stone whilst polishing, and is often omitted now.
A pearl grown by a mollusc following deliberate human insertion of a foreign body to initiate the growth process.
Term used by the diamond grading community to describe the quality of a stone's cut. This is determined by the degree to which the proportions and angles of a stone's facets conform to an internationally accepted standard, known as the 'Ideal Cut'.
This measures a gemstone from its lowest point, the culet, to the surface of the table. The overall depth relative to the stone's other proportions will be crucial in determining the quality of its cut, the level of brilliance seen.
Literally, the splitting of white light into the spectral colours when it passes through the non-parallel sides of a transparent medium. Diamonds show a high level of dispersion, stemming from their high 'refractive index'. The effect in a well-cut diamond is commonly referred to as 'fire'.
The engraving of monograms and inscriptions is a specialised skill. This process is undertaken by hand, using a sharply pointed steel tool, whilst the metal is held on a jewellers block.
One of the small flat surfaces polished onto a diamond during the cutting process.
In some instances the girdle of a diamond may itself have facets polished onto it so as to enhance brilliance.
When the intensity of a diamond's colour is such that it is considered to compliment the stone's appearance, rather than detract from it as a degree of 'off-whiteness', the term 'fancy' is prefixed to the appropriate colour. The strength of colour can then be further qualified by the terms 'light' to 'intense'. EG A yellow diamond might be variously described as: Fancy Light Yellow, Fancy Yellow, or Fancy Intense Yellow.
A loose term sometimes used to describe all cuts or shapes of diamond other than the round brilliant.
This describes the play of colours seen in a well-cut diamond. It is a result of 'dispersion'.
Freshwater Cultured Pearls:
Today these pearls are seen as an attractive and cost effective gemstone, and feature both in fine jewellery, combined with precious metals and diamonds, as well as in fashion or 'costume' jewellery. Refer to our buyers education section on pearls for more detail.
Literally, the waist of the diamond. It forms a thin band that follows the circumference of the stone at its widest point, dividing the upper section, or 'crown', from the 'pavilion'.
A unit of weight used primarily for pearls, and sometimes diamonds, equal to ¼ carat.
Another use of the word is to describe the line along which a diamond may divided by cleavage. This can be visible within a cut stone in the form of a pale plain of slight haziness.
The mark stamped on articles of gold, silver and platinum guaranteeing the purity of the metal, in compliance with legally accepted standards. Hallmarks have evolved since 1300 when they were introduced in Great Britain by Edward 1, and can specify the manufacturer's identity, the location of the assay office, the purity of the metal, and the year of manufacture.
The extreme hardness of diamond is crucial in allowing it to withstand abrasion and retain its beauty after many years of wear. It is this property which also makes diamond an invaluable industrial resource.
Head (also 'Head Size Range'):
The part of the setting which holds a principal gemstone in place. The 'head size range' refers to the range of stone sizes which may be accepted by a particular 'head'.
The term used to describe all imperfections occurring within diamonds and other gemstones. They are a by-product of the formation process and may be considered part of 'nature's fingerprint'. Gemstones with no inclusions are exceptionally rare.
The soft play of spectral colours, as commonly seen in pearls, when it results from the interference of light reflected from the fine layers of semi-translucent nacre.
The term often used to refer to the small particle lodged within a mollusc which results in the growth of a pearl.
Lustre (ref diamonds):
This term refers to the amount of light reflected to the eye from a diamond's surface. Diamonds are associated with a high lustre which is a result of their high level of polish, made possible by their hardness, and also their high refractive index.
Lustre (ref pearls):
This term refers to the characteristic reflection of light by a pearl's surface. The fine platelets of crystals which make up a pearl's nacre result in the combination of exterior shine and inner glow characteristic of pearls.
This term refers to the quality of the cut of a diamond, and is judged by the degree to which its proportions conform to certain internationally accepted guidelines.
The soft tissue within a mollusc. Cultured pearls are grown by inserting an irritant into an incision in the mantle tissue.
A scale of hardness devised in 1812 by Austrian mineralogist Friedrich Moh, to determine the relative hardness of minerals and other substances. The scale ranks ten minerals, with the hardest, diamond, at 10. Its use is limited, as it is non-linear, with the difference in hardness between diamond at 10, and corundum (sapphire) at 9, being greater than the difference between corundum and talc, at 1.
The iridescent inside lining of some molluscs' shells. It is made of the same nacreous substance which creates pearls.
The metal framework in which gemstones are set in the production of a piece of jewellery.
The iridescent substance secreted by the mantle of some molluscs, consisting of calcium carbonate. When fine layers of nacre form around an invasive foreign particle, a pearl is created.
A pearl that forms naturally, or without human interference, when a foreign particle enters a mollusc.
The object inserted into a mollusc's mantle in the pearl culturing process. It is usually a rounded bead of mother of pearl.
The term often used to describe a pearl necklace 32 inches long.
The iridescent, soft 'rainbow' lustre often seen in pearls.
This term is used to describe the secondary colour seen in some pearls, perhaps silver or pink, in addition to their body colour.
A style of setting in which the surface of a jewel is literally 'paved' with numerous small stones set close together.
That part of a cut diamond which lies below the 'girdle' or waist of the stone.
A pearl, whether natural or cultured, is formed when a mollusc (usually an oyster) forms a protective layer around an intrusive object - perhaps a grain of sand - which has somehow lodged within it. This layer is made up of a substance called nacre, and is the same iridescent 'pearly' substance that lines the inside of the shell. In chemical terms, this material is calcium carbonate, in the form of aragonite crystals.
A rare and valuable metal whose silvery-white appearance, high strength and resistance to corrosion make it an ideal setting for diamond jewellery. It is used in the form of an alloy - in the UK, 95% of this alloy is platinum, hence the legal hallmark 950.
A unit of weight for diamonds equal to 0.01 metric carat, the term is mainly used to refer to stones weighing less than one carat. A 0.35 carat stone is said to weigh 35 points.
This describes the external finish of a gemstone. The harder the gemstone the greater the level of polish it will accept, hence the exceptional polish and lustre on diamonds.
A diamond in its natural state, prior to the cutting and polishing processes.
A style of setting in which the stone is mounted within a collar of metal, the upper edge of which has been bent or 'rubbed' over the edge of stone. Also known as 'collet' setting.
One of two traditional methods for dividing a diamond (refer to 'cleave' for the other). A diamond may be 'sawn' perpendicular to its cleavage grain, using a fine disc of phosphorised bronze, coated with a mixture of olive oil and diamond powder, which revolves at high speed. More recently, lasers have been used in the cutting process.
The part of a ring which encircles the finger.
The part of the shank that adjoins the head of the ring. The shoulders of a ring may be set with smaller stones which complement the main stone(s) in the ring's head.
The smaller stones set either to the sides of, or around the principal stone in a ring. When set in the 'shoulders' of the ring, they may be referred to as 'shoulder stones'.
A medium-heavy, malleable metal, usually alloyed with copper to increase its hardness. It can take on a high level of polish, but is liable to tarnish when in contact with sulphurous fumes in the atmosphere. Silver was the preferred setting for diamonds in the 19th century, before being superseded by platinum.
The metal used in the process of making and repairing jewellery for the purpose of joining pieces of metal together. Though it has a marginally lower melting point, solder is made up to exact proportions by metal refiners, matching those of the metal it is being used to join.
South Sea Pearls:
Produced by the larger oyster, Pinctada Maxima, around the warmer South Sea coastlines of Australia, Indonesia and the Phillipines, these pearls range in size from approximately 10-15 mm.
An alloy of silver and copper (which gives it crucial hardness) which conforms to the legal British standard 92.5% fineness, hence the hallmark 925.
The large, uppermost central facet on the top or 'crown' of the diamond.
The cultured pearls from around Tahiti and Okinawa, which range from 8.5 - 15 mm in size. They are a distinctive black or grey, with overtones of blue, green and violet.
A diamond which has been cut in a similar style to the narrow rectangular baguette, but with one end wider than the other, giving a tapered appearance. The function of these stones is normally to add decorative detail to a piece of jewellery, rather than to be the focal point.
The surface colour or lustre of some metals may alter slightly if exposed to certain atmospheric fumes. Silver, for example, tarnishes on exposure to sulphurous fumes, though this can be removed using a liquid that releases the sulphur.
A chain made up of simple oval links of equal length.
A white alloy of gold made up with white metals such as silver, zinc or nickel.