s and their characteristics, 23

Analysis, 5

Aplome, 101

Asters, or asteriated stones, 82, 87-91

Azure-stone, 103

Beryl, 10, 94
colours of, in dichroscope, 34

Beryllium, 10

Bezils, 66

Black stones, list of, 79

Blue sapphire, composition of the, 10
stones, list of, 77

Bone-turquoise, 106

Break, as opposed to cleavage, 19

Brilliant-cut stones, 66

Brown stones, list of, 76

Building up of crystals, 13

Burnt, or pinked topaz, 92

Cabochon-cut stones, 64
(the double), 65
(the hollow), 65

Carbonate series, 11

Carbuncle, 102, 103

Cat of Egypt, 89

Cat's eye stones, 82, 87-91
list of (see "Chatoyant Stones"), 78

Ceylonese cat's eye (see "Cat's eye")

Change of colour (not to be confused with "Play of colour" and "Opalescence,"
which see; see also "Fire"), 36

Characteristics of precious stones, 1, 3

Chatoyant stones, list of, 78

Chemical illustration of formation of precious stones, 8

Chloride of palladium in dichroscope, 34

Chrysoberyl, 88

Chrysolite, 11
ordinary, or "noble", 85
oriental, 85

Cinnamon stone, 102

Claims of precious stones, 4

Cleavage affecting tests, 43
and "cleavage" as opposed to "break", 19, 22

Colour, 26, 28, 30, 32

Colourless stones, list of, 75

Colours and characteristics of the various opals, 35, 36
of precious stones, list of, 75-79

Common garnet, 101
opal, 35

Composite crystals, 13

Composition of paste, or strass, for imitation stones, 71

Composition of precious stones, 7

Converted stones, 72

Corundum, 82

Crown portion of stones, 65, 66

Crystalline structure, physical properties, of 13

Crystallography, 14

Crystals, axes of symmetry, 15
groups of, 15, 16
planes of symmetry, 15
systems of, 16
(1) Cubic--isometric, monometric, regular, 16
(2) Hexagonal--rhombohedral, 16
(3) Tetragonal--quadratic, square prismatic, dimetric, pyramidal, 16
(4) Rhombic--orthorhombic, prismatic, trimetric, 16
(5) Monoclinic--clinorhombic, monosymmetric, oblique, 16, 17
(6) Triclinic--anorthic, asymmetric, 16, 17
treatment of, 14

Culasse portion of stones, 66

Cullinan diamond (see also "Stars of Africa"), 22, 64, 68, 80

Cutting of precious stones, 3, 4, 62

Cymophane, 90

Definition of a precious stone, 1

Diamond, characteristics of the, 80
composition of the, 10
(sapphire), 86
unique, 10
(zircon), 99

Diaphaneity, 26, 28

Diaphano