Amethyst Faceting Information
An Amethyst is the most valuable and precious stone of the quartz family. More often than not are Amethyst facet with good color, cut into fancy stones.
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Color: Purple, violet to red-violet, blue/purple
Moh's Hardness: 7
Refractive Index: 1.544-1.553
Critical Angle: 40.49°
Specific Gravity: 2.63-2.65
Cleavage: None
Fracture: Conchoidal
Dispersion: .013
Heat Sensitivity: Can be. but is usually not a problem
Dichroism: very weak
Birefringence (double refraction): Weak (.009)
Crystal structure: Hexagonal
Treatments: Generally none.
What I prefer to polishing with: Cerium oxide with a Spectra Ultralap.
Jeff's Comments: Cuts and polishes like any other Quartz, usually no problems. I like to use a 1200 Nu Bond lap for pre-polish, it makes the polishing stage faster and easier. Orientating on the "c" is slightly better.
It has been estimated by the GIA and other groups that a significant portion of all commercial cut amethyst is man-made. Synthetic Citrine and Ametrine are also being sold cut as natural stones by some dealers. In most cases the man-made material is being sold as cut stones, but occasionally there is some mixed in with natural parcels of rough. However this is not common. Blue colored quartz is available as a synthetic.
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Is all of that Citrine and Amethyst real?
Design Notes: About any Quartz design will work well. As the rough gets more saturated, I prefer checker boards and bar cuts.
Design Links: 4-Way Stop - This is great for saturated rough if you have a piece that will work in the shape.
Be Still My Heart - Good in about any Quartz
CheckMate - Neat in medium color Quartz
Light House - Nice in any Quartz
Utopia - Classic Barion pear
Jeff R. Graham
The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.
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