This Mozambique ruby has been heat treated, causing an included crystal to melt. The resulting glass occupies less space than the previous crystal, resulting in a frozen gas bubble.

Natural Ruby   •   Mozambique   •   Enhancements: Heat (H)   •   Lighting Conditions: Fiber Optic: Transmitted
Photographer: Richard W. Hughes   •   Image Number: A-001-1317-1   •  Date Posted: 11 June 2015

Pardieu, V., Saeseaw, S. et al. (2015) "Low temperature" heat treatment of Mozambique ruby: Results report. Gemological Institute of America, 16 April, 34 pp.; RWHL*.

When a gem is heat treated, solid inclusions may melt. This photo illustrates two different examples. In the foreground a crystal has melted and cooled into a glass. Because the glass takes up less volume than the earlier crystal, the difference results in a bubble in the glass. Looking further in the background we can see small blue dots. These are the remnants of rutile silk. Heat treatment alters the rutile, sending titanium into solid solution in the corundum. The result is blue “ink spots” surrounding the partially dissolved rutile.

Natural Ruby   •   Mozambique   •   Enhancements: Heat (H)   •   Lighting Conditions: Fiber Optic: Transmitted
Photographer: Richard W. Hughes   •   Image Number: A-001-0607-1   •  Date Posted: 17 March 2015

Pardieu, V., Saeseaw, S. et al. (2015) "Low temperature" heat treatment of Mozambique ruby: Results report. Gemological Institute of America, 16 April, 34 pp.; RWHL*.

A melted crystal of what was probably mica with a trapped gas bubble reveals this Mozambique ruby has been subjected to heat treatment.

Natural Ruby   •   Mozambique   •   Enhancements: Heat (H)   •   Lighting Conditions: Fiber Optic: Transmitted
Photographer: Richard W. Hughes   •   Image Number: A-001-1839-1   •  Date Posted: 05 August 2015

Pardieu, V., Saeseaw, S. et al. (2015) "Low temperature" heat treatment of Mozambique ruby: Results report. Gemological Institute of America, 16 April, 34 pp.; RWHL*.