4.5 cts 12x10x7 MM African Amethyst loose faceted 275E
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100% real not man made but genuine from the earth gemstone.
100% Genuine and natural no treatment.
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Mohs hardness 7
Refractive index 1.544-1.553
Critical angle 40°
Specific gravity 2.63-2.65
Fracture Conchoidal, brittle.
Dispersion Medium (.013)
Heat sensitivity Low
Pleochroism Amethyst very weak (purple to grayish purple); Natural citrine weak (yellow to light-yellow); Prasiolite very weak (light-green to paler green); Rock crystal colorless, no dichroism; Rose quartz weak (pink to paler pink); Natural dark smoky definite (brown to reddish-brown).
Birefringence (double refraction) Weak (.009)
Crystal structure Hexagonal
Cutting Quartz cuts easily. Pre-polishing with 1200 Nubond or 3000 standard lap will make polishing much quicker and more enjoyable.
Polishing Cerium oxide on most common polishing laps.
General Gemstone Details Quartz is a power stone, and has been called as well as considered world wide as the Universal Crystal. It is the most recognized type of crystal, and what many people envision when the thought of crystal comes to mind. In fact there are many different types of Quartz, in quite a variety of colors. Rock Crystal Encompasses a large family of stones and crystals, all of which are made up primarily of silicon dioxide, one of the most common and most important substances in the world. Crystals of pure Quartz, generally six-sided, can be found in all shades and colors. Quartz crystals grow singularly or in groups and take on different shapes according to the temperature at the time of their formation. Quartz crystals can also contain other minerals frozen within, as in Rutilated Quartz. Quartz can be formed of microscopic crystals and take on entirely different appearances and qualities.
Quartz can be a bit of a confusing stone, as it encompasses a great many varieties that often are thought to be gemstones on their own, but are in fact another type of quartz. As well, within the quartz family there are other stones, which have their own little families as well. Here is a breakdown of the most common quartz varieties
Scientific Properties Mohs Hardness of 7 with a trigonal crystal structure. The name quartz comes from the Greek derivative krustallos, meaning ice, as it was thought that quartz was actually ice formed by the Gods. Since the Middle Ages, crystal balls made of rock crystal have been used to predict the future.