hyacinth

Reddish-brown or reddish-brown zircon. In addition to natural red zircon, some zircon can also obtain dark reddish brown or deep red after heat treatment or X-ray irradiation. If the latter is exposed to sunlight for a long time, it will fade, first becoming shallow, then fading to purple, and finally colorless. Natural red zircon is also produced in Hainan Island of China.
Reprinted with attribution： https://cnlocality.com/(Chinese Specialty Products)