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Amethyst is a violet variety of quartz. The name comes from the Koine Greek αμέθυστος amethystos from α- a-, "not" and μεθύσκω ( Ancient Greek) methysko / μεθώ metho ( Modern Greek ), "intoxicate", a reference to the belief that the stone protected its owner from drunkenness. [1] Ancient Greeks wore amethyst and carved ...
Cassiterite. Pleochroic haloes have been observed. Dichroic in yellow, green, red, brown, usually weak, or absent, but strong at times. Cassiterite is a tin oxide mineral, SnO 2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem.
Amazonite, also known as amazonstone, [4] is a green tectosilicate mineral, a variety of the potassium feldspar called microcline. [4] [5] [6] Its chemical formula is KAlSi 3 O 8, [1] [7] which is polymorphic to orthoclase . Its name is taken from that of the Amazon River, from which green stones were formerly obtained, though it is unknown ...
Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is mined in Bolivia. The colour of the zones visible within ametrine are due to differing oxidation states ...
Heat can either improve or spoil gemstone color or clarity. The heating process has been well known to gem miners and cutters for centuries, and in many stone types heating is a common practice. Most citrine is made by heating amethyst, and partial heating with a strong gradient results in "ametrine" – a stone partly amethyst and partly citrine.
A crystal is a solid where the atoms form a periodic arrangement. ( Quasicrystals are an exception, see below ). Not all solids are crystals. For example, when liquid water starts freezing, the phase change begins with small ice crystals that grow until they fuse, forming a polycrystalline structure.
Taaffeite ( / ˈtɑːfaɪt /; BeMgAl 4 O 8) is a mineral, named after its discoverer Richard Taaffe (1898–1967) who found the first sample, a cut and polished gem, in October 1945 in a jeweler's shop in Dublin, Ireland. [4] [5] As such, it is the only gemstone to have been initially identified from a faceted stone.
Ammolite is an opal -like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of North America. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral contained in nacre, with a microstructure inherited from the shell.
Emerald is a gemstone and a variety of the mineral beryl (Be 3 Al 2 (SiO 3) 6) colored green by trace amounts of chromium or sometimes vanadium. [2] Beryl has a hardness of 7.5–8 on the Mohs scale. [2] Most emeralds have many inclusions, [3] so their toughness (resistance to breakage) is classified as generally poor.
Corundum. Corundum is a crystalline form of aluminium oxide ( Al2O3) typically containing traces of iron, titanium, vanadium, and chromium. [3] [4] It is a rock -forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. [7]
