Physical properties / Essential properties / Nature and characteristics / Intrinsic qualities

(1) The crystal form of topaz is rectangular, parallelepiped, and oblong. (2) Its hardness ranges from 8 to 9; therefore, it can scratch crystal (quartz) and is scratched by diamond and sapphire. (3) Its luster is vitreous. (4) Its color is yellow, white, orange, cinnamon, bluish, pink, onion-colored, yellowish-white, greenish-white, mountain green, sky blue, crimson, flesh red, etc. Yellow topaz is extremely fine and attractive. The deeper this color is, the higher its value. In terms of pink color, its details are as follows:

(1) Pink Topaz: This is made from yellow topaz by placing deep yellow topaz in the chillum of a hookah or in a small crucible and covering it with ashes or sand. Afterward, by applying slight heat, its color turns from yellow to pink. If the color turns out fine, the price increases. It is also called Brazilian topaz. (2) Red Topaz: Topaz of this color is rare/prized. Crimson shades are often seen. (3) Bluish Topaz: This is fine and pleasant in color and is not very rare. Light-colored stones (such as aquamarine/beryl) are purchased in its place. (4) White: Also called Minas Novas. It is set in ornaments such as armlets, necklaces, etc. (5) Specific gravity is 3.2. (6) Transparent and lustrous. (7) Reflective/refractive power. (8) Pyroelectricity/piezoelectricity is produced by rubbing and applying heat. The electrical property of Brazilian topaz was first discovered in 1760 by a person named Canton. Abbé Haüy also observed this property in Siberian topaz, noting that this electrical charge can remain in topaz for 20 to 24 hours. While cutting a topaz that had several cavities containing an expansible fluid substance, Sir David Brewster observed a strange phenomenon. His purpose was to make an incision in a cavity, open it, and inspect its liquid substance. Upon opening the cavity, two rapidly expanding fluids began to flow onto the exposed surface and gradually started to expand and contract. Sometimes they would contract into a droplet, and sometimes they would spread out wide. This movement continued until they evaporated. There is no doubt that this motion was due to the electrical charge generated by cutting. (9) Its composition is 58.38 parts alumina, 34.01 parts silica, and 7.61 parts fluorine. (10) Even if it is placed on charcoal and subjected to heat via a blowpipe, it does not melt; however, if heated with borax, it turns into a colorless glass-like substance.