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PRECIOUS STONES
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DIAMOND
Is
the pure crystalline form of carbon, of which bort is the imperfect,
and carbonado the crypto-crystalline. It is found principally in South
Africa; also in Brazil, India, Sumatra, Borneo, Australia, Russia,
China, and very rarely in the United States. Bort comes principally
from South Africa, and carbonado from Brazil only.
Crystallization isometric. It is found as octahedron, rhombic dodecahedron, hexakis octahedron, and otherwise modified crystals.
Hardness, 10; specific gravity, 3.48 to 3.52 (carbonado, 3.14103.41).
Lustre
adamantine; transparent; phosphorescent by heat or solar light. Though
a non-conductor, it becomes positively electric by friction; it is also
electric in the rough.
Cleavage perfect, parallel to the faces of the octahedron; fracture conchoidal or curved.
It is singly refractive (index, 2.439), reflective, and disÂpersive.
Composed of pure carbon.
Infusible, not acted upon by acids or alkalies, but burns in oxygen under intense heat to dioxide of carbon, without residue.
Usual
colors in order of rarity: bluish white, white, yelÂlowish and brownish
white. Rare colors: red, green, blue, pink, violet, orange, canary, and
brown.
Common
imperfections, carbon spots, fractures, feathers, bubbles, white
specks; streak, gray to black. The finer the material the darker the
powder.
Cut brilliant, rose, briollette, pear, heart, marquise, and square.
Symbolizes purity, preserves peace, prevents storms; the month of April.
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