Synthetic alexandrite crystals are made by flux-fusion method by annexing Fe, and Cr manufactured in USA and Japan.
See Alexandrite Tsarstone collectors guide, Definition of Flux-grown synthetic alexandrite, http://m.alexandrite.net/viewpage.html?id=GG-091-00005 (Synthetic alexandrite crystals are made by flux-fusion method by annexing Fe, and Cr manufactured in USA and Japan.) (as of May. 21, 2026, 18:05 GMT).