Hemihedral. Having
only half the planes or facets which a symmetric crystal of the type to
which it belongs would possess; a crystal wanting some of its planes.
(The hemihedral form in crystallography produces or aids the phenomena
of pyroelectri-city.)
Hexagonal. Of the form of a hexagon; having six sides or angles.
Hydrostatics. Pertaining to the principles of the equilibrium of fluids.
Inclusions. Foreign substances within the body of a transparent mineral.
Indian-Cut. A
style of diamond-cutting usually of Indian or other Oriental origin in
which the table is usually double the size of the culet; such stones
are generally reçut for European or American requirements.
Iridescence. Descriptive of prismatic colours appearing within a crystal.
Isometric. The cubic system in crystallography.
Jägers. Bluish-white diamonds of modern cut; originally diamonds from the Jagersfontein mine.
Jig. (Jigger; Pulsator.) A riddle or sieve shaken vertically in water to separate ore or gem gravel or ground into strata.
Knipe-Edge. The girdle of a brilliant cut to a sharp edge and polished.
Knots. Conditions found in diamonds as in wood, and troublesome to the lapidary.
Lapidary. One who cuts, polishes, or engraves precious stones.
Light Yellow. Seventh grade diamonds.
Lumpy. Stones cut thick.
Lustre. The
optical character of a gem, dependent upon that portion of the light
falling upon it which is reflected from the surface. Degrees of lustre:
splendent, shining, glistening, glimmering. Kinds of lustre: metallic,
vitreous or glassy, adamantine (the diamond's lustre), silky, satiny,
pearly, nacreous, greasy, waxy, resinous.
