diaphanous stones, 28

Shining, in lustre, definition of, 29

Silica group, composition of the, 11

Silicates, 100

Silky-lustre stones, 28, 29

Single-refraction (see "Refraction")

South African diamond (see "Cullinan Diamond")

Specific gravity, 45

Splendent, in lustre, definition of, 29

Splitting of the Cullinan diamond, 22

Star-portion of stones, 65

Stars of Africa (see also "Cullinan Diamond"), 22, 64, 68

Starting or splitting of stones on cleavage planes, 23

Step-cut stones, 66

Stones arranged according to colour, 75-79
hardness, 39-41
specific gravity, 48-50

Strass for imitation stones, composition of, 71

Sub-metallic in lustre, definition of, 29

Sub-translucent stones, 28

Sub-transparent stones, 28

Succinite, 102

Synthesis, 5

Systems of crystals (see "Crystals")

Table-cut stones, 65

Tallow drops, 65

Teeth of stone, 65

Testing by crystalline structure, 17
hardness, 40, 43
with needles, 41
gems by dichroscope, 33, 34
solution (Rothschild's), 73

Tests of precious stones (general), 70

Topaz, 11, 91
colours of, in dichroscope, 34
oriental, 85

Topazolite, 101

Tourmaline, 96, 97
electric experiments with, 58, 59

Translucent stones, 28

Transmission of heat, 52-56
light, 26

Transparent stones, 28

Trap-cut stones, 66

Tri-morphism in precious stones, 25

Triplets, 72

Turquoise, 104
(bone), 106
composition of the, 11
odontolite, 106

Uwarowite, 101, 102

Violet stones, list of, 78

Vitreous-lustre stones, 28, 29

Water-sapphires, 86

White (paste) stones, 71
stones, list of, 75

Yellow stones, list of, 76
topaz, 92

Zircon, 10, 98
diamonds, 99

Zirconium, 10

LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED,
GREAT WINDMILL STREET, W., AND DUKE STREET, STAMFORD STREET, S. E.

End of the Project Gutenberg EBook of The Chemistry, Properties and Tests of
Precious Stones, by John Mastin

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