Glossary: D - H

Dark center/table Occurs in stones which have been cut too deep.
Dead stone Stone without brilliance caused by many/big inclusions.
Diamond A mineral that crystallizes and is composed of carbon. Has a refractive index of 2.41
Diamond simulations Any substance made to imitate a natural diamond. Such as moissonite, Cubic Zirconium.
Dispersion Display of spectral colors seen in a diamond also called: 'Fire'
Emerald cut Rectangular diamond shape.
Extra Facet An additional facet, not usual for the cutting style. Placed to remove imperfections.
Facet Flat polished surface part/plane; formed to increase brilliancy.
Faceted girdle Girdle that has many small facets around the circumference of the stone.
Fancy color Diamond with an attractive color other than white or slight yellow.
Fancy shape Diamond shape other than a round cut diamond.
Feather  Fracture in the diamond. Often white and feathery appearance. Also called cleavage or Gletz.
Finish  Polish & symmetry
Fire  Display of spectral colors seen in a diamond also called 'Dispersion'.
Fish eye Circular reflection of the girdle visible through the table. Caused by a shallow pavilion.
Fluorescence Some diamonds will emit visible light (usually blue or green) when put under ultraviolet lamp.
4 C's Cut,color,clarity & carat: Four main diamond value characteristics.
Full cut diamond Brilliant cut, with 57 or 58 facets
Gemologist Person who completed the studies in gem identification & grading.
GGG Gadolinium Gallium Garnet. Diamond imitation/stimulant.
GIA Gemological Institute of America. A nonprofit organization that offers gemstone identification/certification, buying advice
to consumers and training to those in the jewelry trade.
Girdle Edge around the widest part of a polished diamond.
Hardness Gemstone's ability to resist scratching.
Heart shape  Diamond shape in the form of a heart.
Hearts & arrows  Feature that show with ideal cut diamonds. 8 hearts can be seen through the pavilion side & 8 arrows through the crown side with aid of a viewer.
HPHT High Pressure High Temperature Process: used for color enhancements.
HRD Hoge Raad voor Diamant. Non profit institute in Antwerp (Belgium) which offers gemstone certification and training for the diamond trade.