Synthetic star sapphires and rubies produced by wiede's Carbidwerk, Freyung, Germany

Asteriated synthetic rubies and sapphires were produced by Wiede's Carbidwerk of Freyung, Germany, between the mid-1950s and the end of the 1970s. The rough crystals were grown slowly through a proprietary variant of the Verneuil method, developed in the mid-1950s, in the form of almost spherical to elliptical boules. After crystal growth, rutile needles were exsolved by annealing at temperatures ranging from 1100°C to 1500°C. Notably, such needles were somewhat shorter than those generally produced in asteriated material from other Verneuil manufacturers, particularly linde in the United States, giving the cabochons a slightly different visual appearance. Furthermore, the production process using oriented seeds and a variable temperature-time protocol resulted in samples consisting of up to three growth zones. Such properties may aid in identifying Wiede's synthetics produced up to the end of the 1970s.