Mystic Topaz, the most frequently seen coated topaz, is produced using the physical vapour deposition (PVD) coating process. Applied to top quality natural white topaz, the process can induce an iridescent, multi-coloured appearance, similar in appearance to shot-silk.
00000The coating however is quite delicate and scratches easily. Once scratched the stone cannot be repolished

R. I. - 1.63-1.64 

Hardness - 8