Sapphires
The sapphire monocrystalline noble variety of aluminum oxide is one (To the 2O3), a famous mineral like corundum, strongly (v. color of minerals) and only natural substance of hardness 9 in the Scale of Mohs. Officially the term sapphire is only the variety blue-blue of the corundum, but in reality its various coloration from that red one comes used for indentificare any, called steals. Other varieties are that orange, call padparadscia and the armofane of color opaque gray. The color typical blue-blue of the gem derives from inclusions of iron and titanium. In the event in which the inclusions they were oriented in particular ways, the phenomenon of the asterismo (like from photo can be introduced). It can be found in nature in metamorfiche cliffs deriving from remelting of a micascisto, of a quartzite or of a limestone, in poor magmas of silice and in their you respect to you I placed to you alluvial. One remembers the Australian layers on purpose, of the Sri Lanka, the Birmania and the Thailandia. The diffused cut more for such gem is that round oval or, but other typologies are not excluded, like the heart one or baguette one. Between known gems of exceptional dimension, it goes cited the “Star of India”, of 563 carats, conserved near the Natural History Museum of New York. It comes used for the quadrants of the clocks and the windows of the airplane. The particularly opaque crystals and not elevated quality, or their analogous synthetic ones, come take advantage of to you as I abraded to you, in the clocks or for the aluminum extraction.