Rubies from Mong Hsu

Abstract

Large quantities of rubies-both rough and faceted-fron~ a con~merciolly important new source in Myanmar (Buirn~n) hmve been avaiIcrble on the Bangltolt inarltet since 1992. The nzby crystrrls from the Mong Hsu marble deposit have clipymmidnl to barrel-shaped hobils and reverrl dark violet to almost black "cores" 017d red "rims." With heat treatment, which removes their blue color componer~t, the cores become intense red. The rubies grew umder varying conditions in complex growth sequences. The color distribution between cores and rims is related to a different incorporation of chrorniun~ andlor titanium during crystnl growth. Gemological, microscopic, chemical, and spectroscopic properties presented here permit the separal.ion of faceted Mong H s ~ i nibies from their syntlietic and other natural counterpclrls. Problems arising hon7 artificinl fracture fillings nre also addressed.