Glossary: O-Z

Off-make Poorly proportioned diamond.
Off-center culet When the culet is not in the middle of the stone, often due to re-polishing.
Oval cut Diamond polished in a elliptical or oval shape.
Pavilion Part of diamond which lies below the girdle, forming the pointed side.
Pear cut Diamond polished in the form of a tear drop or pear.
Pinpoint Internal characteristic. Tiny spots within the diamond.
Plot(ting diagram) Schematic drawing on a diamond certificate, illustrating the location of the most prominent internal & external characteristics of the certified stone.
Point Weight measurement of a diamond. 1/100 of a carat.
Polish Smoothness of the diamond surface.
Polish Lines Tiny parallel lines on the diamond surfaces caused during polishing.
Polish mark Burn mark, caused through diamond dust melting into the surface of the stone
Polished Girdle A girdle that has been polished.
Princess cut Fancy shape that can be square to slightly rectangular.
Reflection The return of light that strikes the surface of the diamond.
Refraction The change in direction of a ray of light as it enters a diamond.
Rough diamond Unpolished, uncut diamond as it occurs in nature.
Rough Girdle Unpolished, un-faceted girdle.
Scintillation Mirror-like reflections from the diamond facets as it turns in the light.
Single Cut A brilliant cut, of which only the main facets have been polished. Being:  8 bezel facets, 8 pavilions, table & culet.
Star facets Triangular facets which surround the table facet of a brilliant cut diamond.
Symmetrie Quality of the fashioning : the overall balance of the shape & facet alignment.
Synthetic diamond A manmade diamond, it is a real diamond but has not been formed naturally.
Table Horizontal flat top facet on the crown of the diamond.
Treated gems Gemstones which have received artificial color and/or clarity enhancement.
Twinning whisp Cloudy area produced by crystal structure distortion.
Wavy girdle Poorly polished girdle, not parallel with the table.
YAG Yttrium Aluminum Garnet : diamond imitation/stimulant