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A to Z of Diamonds Glossary
Alphabetical list of main words and terms relating to diamond or diamonds, containing over 600 entries, with definitions, explanations and links to more detailed information.

SandA term used in sorting rough diamonds for size. It usually refers to stones under about 0.10 carats (10 points).
ScaifeA steel wheel which is diamond impregnated, for polishing diamonds. Pronounced skife, we have also seen the spelling skyf.
Science To a scientist diamond is interesting for its range of exceptional and extreme properties. When compared to almost any other material, diamond almost always comes out on top. As well as being the hardest known material, it is also the least compressible, the stiffest material, the best thermal conductor with an extremely low thermal expansion, chemically inert to most acids and alkalis, transparent from the deep UV through the visible to the far infrared, and is one of the few materials known with a negative electron affinity.
SeaA colour description used for certain fancy bluish green diamonds, also "Eau de Mer".
Semi Precious, Semi-PreciousAn expression traditionally used to describe gemstones other than the "big four" of diamond, ruby, sapphire, and emerald, so would include opal, pearl, amethyst an more. CIBJO and others have advised that its use be discontinued, and all gemstones be termed "precious", a recommendation which has been almost universally ignored.
SetThe process of securing a diamond or other gem into a piece of jewellery is known as setting it.
SetterPerson who puts diamonds or other gems into jewellery mounts.
SettingThe process of fixing a gemstone into a mount to create a piece of jewellery. A setting is a word used by consumers to describe what a jeweller would call a mount. The word setting is sometimes used in referring to a collet.
ShapeA word often used interchangeably with "cut", although the two have different meanings. Shape should refer to the basic outline type, such as round, oval, square, princess, radiant, cushion, oblong, emerald, baguette, pear.
ShapesA term used when sorting rough diamonds. "Shapes" are unbroken crystals, but of less regularity than "stones".
SiberiaSiberia has been a major source of diamonds for a long time, with new investments in existing mines set to increase production soon.
Sierra LeoneDiamonds are the most important export from Sierra Leone, although the country is still unstable following a long period of civil war.
SieveA device for sorting rough or polished diamonds by size. Diamond sieve sets have interchangeable sieve plates each drilled with a number of holes.
Sight, SightsEach of the week long meetings which De Beers hold ten times each year for rough diamond buyers who attend by invitation.
Sightholder, Sight-holderAn individual or company which attends De Beers diamond selling meetings, known as sights.
SignetA ring designed to carry a personal seal, often set with a diamond. Signet Group PLC is the name of Ratners PLC which owns H. Samuel and Ernest Jones in the UK.
SilverWhite highly reflective metallic element, used in Victorian times for diamond setting, before the development of white gold alloys, and before platinum could be isolated.
Silver CapeAn obsolescent colour grading term denoting diamonds whiter, or less yellow than light cape.
Silver WeddingAlthough silver is a traditional gift on the 25th wedding anniversary, a diamond eternity or other ring is often acquired.
Simulate, Simulated, SimulantA simulant is anything, natural gemstone or synthetic, which imitates a diamond. Synthetic diamonds however are real diamonds, not simulants.
Single CutConfusingly, another name for eight cut diamonds, with 18 facets.
Single RefractionDiamond is normally singly refractive, many gemstones are doubly refractive (bi-refringent), and diamonds can also be doubly refractive because of internal strain or inclusions.
SkinCoating on the surface of many rough diamonds.
Slight Inclusions, SI, SI1, SI2A clarity grade used by GIA and others, an SI stone should not have inclusions visible to the naked eye.
SI3A clarity grade between SI2 and P1 (I1), not recognised as yet by the GIA, but in use by EGL and Rapaport, plus most of the wholesale diamond trade.
SmallSlightly variable term used to describe size ranges of polished diamonds, usually meaning any weight under about 0.08 cts (8 points).
SmallsA term used when sorting rough diamonds by size. Usually refers to stones of about one carat or over, depending on the general quality of the source.
Smuggle, Smuggler, SmugglingBecause of diamond's high value in relation to its size, diamonds are very easy to transport, either as personal wealth for evacuees, or for commercial smugglers.
SOC, S.O.C.Initials of De Beers "Supplier of Choice" policy (q.v.), actually a misnomer as it should really say "Customer of Choice".
SolitaireA ring or other piece of jewellery containing a single diamond, or sometimes a single major diamond with smaller diamonds as embellishments.
SortTo split rough or polished diamonds into grades depending on colour, clarity, size. Also to separate rough diamonds from their surrounding materials.
South AfricaStill one of the world's major source of diamonds, although its share of production has declined. It is now about 5th largest producer by weight, and 4th by value.
SouthernEra Diamonds Inc.SouthernEra is engaged in diamond exploration in Canada, South Africa, Gabon, Australia and the Democratic Republic of Congo. It recovered its first Congolese diamonds in October 2005.
SpamSome unsolicited commercial e-mail (spam) allegedly involves diamonds. Typically the vendor has £20 million worth of stolen diamonds he will sell you for 20% of their value in exchange for your help. Ignore!
SpecificationsFollowing Tolkowsky, a number of individuals and organisations have published specifications for excellence in diamond cutting, particularly in relation to proportions and angles.
SperregebietSperregebiet means "Forbidden Territory", and is a part of Southern Namibia. It got its name after diamonds were discovered in 1908, in what was then German South West Africa.
SpinelA natural gemstone which occurs in many colours. Synthetic white spinel was often used in the past as a diamond substitute.
SpottedA clarity grade below P3 (I3), now in danger of become obsolete, as P3 appears to have been extended to include lower grades.
SpreadThe diameter of a diamond or the normal weight equivalent assuming ideal proportions. Also used to describe a diamond which is cut too shallow, and therefore "spreads" more than it weighs.
StarA fancy shape of polished diamond. A facet name. Small polished diamonds, usually under about one point (0.01 cts) each.
Star FacetOne of the eight facets adjacent to the table on a brilliant cut diamond, so called because they from an eight pointed star when viewed from above.
Star of South AfricaThe first large diamond found in South Africa, at 84 carats rough, and 48 polished, it sparked the diamond rush. Also known as the Dudley diamond.
StarsSmall polished diamonds, usually under about one point (0.01 cts) each.
SteinmetzThe Steinmetz Diamond Group is a major diamond cutting and trading company.
Step CutA traditional method of facetting square, emerald and other shapes, the facets are in the form of sloping "steps", these cuts fail to capture most of the potential brilliance of diamonds, and will almost certainly be largely superseded by modified brilliant styles of cutting.
Stone, StonesA general word for any gemstone including diamond. Also a shape grade used when sorting rough diamonds. A "stone" is an unbroken crystal of regular formation.
Strategic StockpileAs with many essential commodities, the USA holds a strategic stockpile of diamonds. There is an interesting chapter in Epstein's book about supplies of diamonds during the second world war.
Sunflower CutOne of a number of "flower cuts" developed by Gaby Tolkowsky in about 1997 for De Beers.
SupermaterialThere are many unusual, unique, or extreme properties of diamond which would qualify it as a supermaterial.
Supplier of ChoiceA controversial De Beers policy to restrict its supply to customers who will carry out its policies regarding advertising promotion and branding, furthering claims about it monopolization of the diamond industry.
SuratMajor diamond polishing town in India.
SurfaceWhether a polished diamond has a good surface, free of blemishes, is a quality factor.
Surface GrainingUsually parallel lines visible on the surface or facet edges of a diamond, similar to grain in wood. These grain lines reflect the structure of the diamond crystal, possibly an area of twinning, and may be due to imperfect polishing.
SwazilandThis African country is a fairly important diamond source.
Swiss CutHalfway between a brilliant and an eight cut, with 34 facets in total.
Symmetrical, SymmetryIn most cuts of diamond, symmetry is important and desirable.
SyndicateOne of the names by which De Beers, with its inter-related companies, is known. Many diamond syndicates have been formed at various periods of time, to purchase large important diamonds.
SyntheticReal diamonds which have been manufactured rather than mined. Do not confuse with imitations.

There are currently over 600 entries in this table.
Over 90 of them have page links to a page on this site. Eventually, we intend to add a more complete description for most entries, each on its own page. Please watch this space! the Lowest Possible Price

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