Mong Hsu rubies are generally heat treated to remove the blue cores that darken their color. In addition, most contain open fissures that disfigure the gems. Treaters use fluxes like borax to heal the fissures with microscopic amounts of synthetic ruby, which recrystallizes in the cracks. This photo shows a flux-healed fissure, accompanied by a cottony cloud of diaspore silk.
Natural Ruby • Myanmar (Burma); Mong Hsu • Enhancements: Heat + Fissure Healing (H-FH) • Lighting Conditions: Fiber Optic: Oblique
Photographer: Richard W. Hughes •
Image Number: A-001-0765-2 • Date Posted: 07 April 2015
Hughes, R.W. and Emmett, J.L. (2004) Fluxed up: The fracture healing of ruby. The Guide, Vol. 23, Issue 5, Part 1, Sept.–Oct., pp. 1, 4–9; RWHL*.
Peretti, A., Schmetzer, K. et al. (1995) Rubies from Mong Hsu. Gems & Gemology, Vol. 31, No. 1, Spring, pp. 2–26; RWHL*.