Best Gemstones | Luxury Gemstones

Common Terms Used With Gemstones

Abrasion – Damage to a facet edge, culet or keel line.

Adamantine – Quality of luster – like that of a diamond.

AGS – American Gem Society, Las Vegas, USA

Baguette – Rectangular narrow gem cut.
Tapered – Gemstone cut in a trapezoid shape, one end narrower

Beard – Featherlike inclusion located on the girdle of a diamonds and usually a result of improper bruting.

Bezel – Angled surface on a gemstone’s crown – between girdle and table.

Bow Tie – Term used to describe a dark area seen through across the table of a diamond.

Briolette – Pear shaped faceted gemstone

Brilliance/Luster – Intensity of the light reflecting from a gem, observed through the crown.

Brilliant Cut – Collective name for diamond cuts where lower facets radiate from the center of the gem towards the girdle – round cut is most common.

Bruise – Crumbled area on a cut gem’s surface, caused by a blow.

Buff Cut/Cab Top – A cut combining the features of a cabochon top with a faceted pavilion. Popular in men’s jewelry. Minimizes facet junction abrasion.

Bruting – A process of shaping the girdle of a rough diamond.

Burn Mark – Mar on a gemstone facet surface due to overheating during polishing.

Cabochon – A gemstone fashioned with a domed or convex smooth and polished surface.

Cape (Color) – A term used to describe yellow diamonds found in the M to Z range of the color grading scale.

Carat – Standard unit of weight for gemstones – 1 carat = .2 gm

Cavity/Pit – An opening or indentation on the surface of a gemstone).

Certificate – Document provided by accredited laboratory defining a gemstones type, weight, color, clarity, proportions, finish grade, treatments. etc.

Chaton – A generally spherical stone that is faceted.

Clarity – Relative freedom from inclusions and imperfections of a gemstone. Usually expressed in a fixed grading scale for diamonds.

Cleavage / Feather – Break or fracture in the stone, internal or external and usually occurring along the crystal’s growth planes).

Cleavage Plane – Plane parallel to a crystal face.

Cloud – Milky area in a gemstone; made up of a multitude of very small inclusions.

Color Diamonds – Range from white to brown of a diamond and usually defined by standard nomenclature. Generally ranges from D – M.

Color Change – Ability of a gemstone to change hue/color when viewed under different types (wavelengths) of light. e.g. Alexandrite, color change sapphire.

 Colored Gems – The dominant hue of a gem. Identified by position on color wheel or by wavelength.

Crown – Portion of gem stone above the girdle.

Crystal inclusion – A crystal in a gemstone. Common in certain species of colored gems

Culet – Point or small facet at the convergence of pavilion facets.

Cushion – Square or rectangular cut with rounded corners. Numerous variations.

Cut – Proportions, make and finish of a polished gemstone.

D – Best color grade for diamonds. Very white.

Dead stone – A gemstone so heavily included that no brilliance can be observed.

Dispersion – Intensity of light observed through the crown of a gemstone.

Emerald Cut – Rectangular or square step cut with diagonal corners.

External characteristics – Imperfection on a gemstone’s surface.

Facet – Flat polished surface on a finished stone.

Faceting – Process of creating facets on a gemstone.

Fancy color – Naturally colored diamonds with varying degrees of rarity.

Fancy Shape – Any shape other than a brilliant cut.

Fashioning – Process of manufacturing, i.e. designing, cleaving, sawing, bruting pre forming, cutting and polishing.

Feather – Break or fracture in a stone, internal or external.

Finish – Quality of a gemstone’s polish.

Fire/Brilliance/Internal Luster – Intensity and quality of light reflecting from a gemstone and observed through the crown.

Fish eye – Usually diamonds where pavilion is too shallow. Result is a circular reflection of the girdle that can be seen through the table.

Fluorescence – Visible light occasionally emitted from diamonds during exposure to ultraviolet light.

C’s – Carat, Cut, color & Clarity; four of the factors used in determining the value of a gemstone.

Gem / Gemstone – Mineral or organic material with sufficient beauty, rarity and durability to be set into jewelry.

GIA – Gemological Institute of America,Carlsbad,USA

Girdle – Edge located between a gemstone’s pavilion and crown.

Girdling – Process of shaping the rough stone’s girdle.

Grain – Weight unit equivalent to 0.25 carats.

Graining – Natural irregularities seen internally or externally in the crystal structure of a gemstone. Often mistaken for polishing lines.

Hardness – A gem material’s resistance to wear/ scratching measured on Mohs hardness scale.

Heart Shape – Modified brilliant cut with heart-shaped girdle, usually 56 facets. Cut is often to remove inclusions in an otherwise cleaner gem.

Hearts & Arrows – A gem cut to ideal proportions &l symmetry. Shows eight hearts shapes in a pavilion view and eight arrows in a crown view, but only when observed through special viewers.

HRD – Hoge Raad voor Diamant (Diamond High Council), Antwerp, Belgium

IDC – International Diamond Council, Amsterdam, The Netherlands

IGI – International Gemmological Institute, Antwerp, Belgium

Imperfection – Blemish in a stone which occasionally reaches the exterior.

Included – One clarity grade which refers to eye-visible inclusions. I1,I2,I3.

Inclusion – Internal characteristic.

Industrial diamonds – Non gem quality diamonds.

Internal characteristics – Imperfection located within the stone.

Internal reflection – Light reflected off an internal surface of a gemstone.

Kimberlite – Volcanic diamond-bearing rock (also called blue ground).

Laser Cut – Fashioning a gem’s eventual shape using a laser

Laser Inscription – Laser engraved identifying text or numerals, usually on the girdle.

Laser Sawing – Laser division of a crystal.

Leveridge Gauge – Tool used to measure dimensions of a mounted or unmounted gemstone.

Lively stone – A stone with good brilliance and luster.

Loupe – Small magnifier used to examine gems. Usually 10X.

Loupe Clean – No inclusions seen under 10X magnification.

Make – Quality of symmetry and finish of a polished gem.

Marquise – Symmetrical boat shaped brilliant cut gem with pointed ends.

Masterstones / color samples – A set of polished gems which have been color graded by an accredited laboratory. Used to color-grade diamonds.

Mohs – Scale used to determine the hardness of minerals.

Natural – An original surface on a rough gemstone that is left untouched on the polished stone. Usually found on girdle.

Nick – Small chip on a gem surface or facet junction usually as result of contact with other stones.

Oval – Modified brilliant cut with an obround shaped girdle outline.

Parcel Paper – Folded papers used to hold polished or rough diamonds.

Pavilion – Part of a gem below the girdle.

Pavilion facet – Polished surface on the pavilion of a gem.

Pear Shape/Teardrop – Asymmetrical cut with one pointed and one rounded end.

Percussion Mark – crumbled area on the surface of a fashioned gem and normally resulting from a blow – usually white.

Pinpoint inclusion – Very small inclusion of any color indistinguishable as a crystal.

Pit/Cavity – Small opening on the surface of a polished stone.

Point – Weight unit, .01 (1/100) carat.

Pointer – Term used in describing polished stones under 1 carat.

Polishing lines – Small parallel marks left on facets during the polishing process.

Polishing wheel – Flat cast iron wheel upon which gems are polished.

Princess – Modified brilliant cut with a square or rectangular girdle outline featuring 57 facets.

Proportions – Relative symmetry of angles and measurements on a polished gem.

Quality – Term used to descibe the overall color, clarity and cut attributes of a stone.

Radiant – Rectangular gemstone cut, often 70 facets, combining the shape of an emerald cut and sparkle of a brilliant.

Reflection – Return of light to the eye after striking an external or internal surface of a facet.

Rose Cut – Cutting style that produces a flat un faceted base and a dome-shaped top covered with a variable number of triangular facets and terminates at a point.

Rough – Gem at found in nature before undergoing any manufacturing process.

Round Cut – Round brilliant cut.

Sawing – Process during which a rough gem is cut.

Scratch – Damage to a polished facet, usually appearing as a faint white irregular line. Often due to contact with other gems.

CSI – Clarity grade meaning slightly included: SI1 and SI2.

Simulants – Natural or synthetic substances meant to resemble a genuine gemstone.

Star Facet – Triangular facet on the crown of a brilliant cut next to the table.

Symmetry – The accuracy with which a gem is fashioned to a mirror image.

Synthetic – Non-natural, laboratory produced.

Table – Large face tat the center of the crown.

Thermal Conductivity – Ability of a material to conduct heat.

Trillion – Cut triangular shaped often 44 facets.

Ultraviolet – (Above Violet) Upper end of the light spectrum and invisible to the human eye. Shows fluorescence in gemstones.

VS – Gem clarity grade meaning Very Slight; VS1 & VS2.

VVS – Gem clarity grade meaning Very Very Slight; VVS1 & VVS2.

Wavy Girdle – Girdle in a gemstone which has been improperly fashioned and does not run evenly.

Weight – Gem weight measure – carats, subdivided in grains and points.

White – A term to describe colorless gems and diamonds D- H color grade.

Yield – Carat weight remaining after polishing – often expressed as a % of rough weight.

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