Small, blocky black uraninite crystals and rounded, transparent zircon crystals such as these are commonly found in Sri Lankan sapphire. While at first their shiny halos may seem like evidence of heat treatment, they can actually occur naturally, as in this stone. The undissolved rutile silk needles in this stone demonstrate that it has not been heated at a high temperature.
Natural Star Sapphire • Sri Lanka (Ceylon) • Enhancements: None Detected (None) • Lighting Conditions: Dark Field
Photographer: E. Billie Hughes •
Image Number: A-001-3320-3 • Date Posted: 20 November 2015
Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 3. Basel, Switzerland, Opinio Publishers, 672 pp.; RWHL*.