Hyperion • Inclusion Search Engine • Lotus Gemology
This Thai/Cambodian ruby displays thin films with drippy, irregular edges and a melted crystal inclusion featuring an immobile gas bubble. These features act as evidence that the stone has been heat treated.
When a gem is heated, it and everything contained in it expands, governed by each material’s coefficient of thermal expansion. Should an included crystal expand more than the host, the result is a tension fissure, such as this around a mica crystal in this heated Mozambique ruby.
When a gem is heated, certain inclusion may dissolve or melt. In this case, it appears that the white crystals have dissolved/melted, creating a dendrite-like healing pattern in the surrounding fissure. Also visible are clusters of small crystals of what is probably zircon.
Cube-shaped white crystals with glassy fissures around them in a heated ruby. Crystals such as this with sharp, angular shapes will often produce fissures such as this when heated (moreso than a rounded crystal).
A fingerprint, or partially healed fissure, in a heated Thai ruby. Note the rounded, slightly melted edges.
Several crystals in this ruby from Madagascar are surrounded by small reflective fissures.
A small crystal with a shiny discoid attached can be seen clearly against a backdrop of orange color zoning in this ruby from Madagascar.
“Saturn inclusion” type crystals, as seen here, are a hallmark of Thai/Cambodian ruby. Although we were unable to identify the composition of the whole crystal, the black spots on the surface were identified as magnetite with micro Raman.
Thin films, as seen here, are a classic inclusion in Thai/Cambodian ruby.
Further evidence is found by carefully examining the mixed crystal exsolved rutile silk. Such inclusions typically unmix into two different solid phases, one highly reflective and the other of lower relief. When such crystals are heated, the lower relief crystals may begin to break down, developing irregular white patches, as one can see here, particularly in the crystal at the center left of the field of view.
Spall marks on the surface of this Mozambique ruby prove that it was heat-treated after cutting and polishing.
Spall marks on the surface of this Mozambique ruby prove that it was heat-treated after cutting and polishing. Note that some of the spall marks have dark halos around them.
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