Swiss Blue Topaz

Chemical Formula: Al2SiO4(F,OH)2 Fluor containing aluminum silicate
Refractive Index:1.619-1.627
Hardness：8 Mohs
Orignal:Brizil,Nigeria ect.

Natural Colorless Topaz is exposed to radiation (a process known as irradiation) and then usually heated,
to produce striking blue colors. The color treatment is usually performed on grayish-blue or silver-gray gemstones.
Medum blue is called "Swiss blue”.The darker blue shades are more valuable.Blue topaz was
a powerful stone that could increase the strength of the wearer and even provide invisibility in desperate times.