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Gem-Stones and Their Distinctive Characters

Chapter 120: TABLE II
By George Frederick Herbert Smith
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About This Book

A practical handbook describing the physical characters and identification methods for gemstones, combining clear accounts of crystalline form, optical properties (reflection, refraction, dispersion, double refraction), colour and absorption effects, specific gravity, hardness and electrical behaviour with practical techniques such as refractometer use and heavy-liquid tests. It outlines cutting, weighting and nomenclature, distinguishes manufactured and imitation stones, and provides species-by-species descriptions of precious and semi-precious gems — including diamond, corundum, beryl, topaz, spinel, garnet, tourmaline, zircon, quartz and chrysoberyl — accompanied by diagrams, plates and tables of physical constants for practical reference.

TABLE II

Colour of Gem-Stones

Colourless and White.—Diamond, corundum (white sapphire), topaz, quartz (rock-crystal), zircon (when ‘fired’), moonstone; rarely beryl, tourmaline; among the less common species, phenakite, spodumene (colourless kunzite), beryllonite.

Yellow.—Diamond, topaz, corundum (yellow sapphire), quartz (citrine, Scotch or occidental topaz), tourmaline, zircon, sphene, spodumene, beryl.

Pink and Lilac.—Corundum (pink sapphire), spinel (balas-ruby), tourmaline (rubellite), topaz (usually when ‘fired’), spodumene (kunzite), beryl (morganite), quartz (rose-quartz).

Red.—Corundum (ruby), garnet (pyrope, almandine), spinel (balas-ruby), tourmaline (rubellite), zircon, opal (fire-opal).

Green.—Beryl (emerald, aquamarine), peridot, corundum, tourmaline, chrysoberyl (including alexandrite), zircon, garnet (demantoid); among less common species, spodumene (hiddenite), euclase, diopside, idocrase, epidote, apatite, obsidian; rarely diamond; also semi-opaque, turquoise, jade.

Blue.—Corundum (sapphire), spinel, topaz, tourmaline, zircon; among the less common species, kyanite, iolite, benitoite, apatite; rarely diamond; also semi-opaque, turquoise, lapis lazuli, sodalite.

Violet and Purple.—Quartz (amethyst), corundum (oriental amethyst), spinel (almandine-spinel), garnet (almandine), spodumene (kunzite), apatite.

Brown.—Diamond, tourmaline, quartz (smoky-quartz); among the less common species, andalusite, axinite, sphene.