Let's Learn About Gemstones

Wiki links for some gemstones 

Turquoise

"Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl6(PO4)4(OH)8·4H2O. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue. In recent times turquoise, like most other opaque gems, has been devalued by the introduction of treatments, imitations, and synthetics onto the market, some difficult to detect even by experts."

Malachite

"The stone's name derives (via Latin and French) from Greek molochitis, "mallow-green stone", from moloch%u0113, variant of malach%u0113, "mallow". Malachite was used as a mineral pigment in green paints from antiquity until about 1800. The pigment is moderately lightfast, very sensitive to acids and varying in colour."

Chalcedony

Chalcedony From Wikipedia, the free encyclopedia Jump to: navigation, search
Chalcedony knife, AD 1000-1200
Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of the minerals quartz and moganite[1]. These are both silica minerals, but they differ in that quartz

Kyanite - Wikipedia, the free encyclopedia

Kyanite From Wikipedia, the free encyclopedia Jump to: navigation, search
KyaniteGeneral
Category
Mineral
Chemical formula
Al2SiO5
(aluminium silicate)
Identification
Color
Blue; also green, white, grey, black
Crystal habit
Columnar; fibrous
Crystal system
Triclinic
Cleavage
[100] Perfect, [010