Heated Sapphire Inclusions

First Published: 7 September 2026

Heated Sapphire Inclusions

Explore inclusions in heat-treated sapphire in Hyperion, the Lotus Gemology inclusion database. Hyperion contains photomicrographs of inclusions and internal features in natural sapphires that have been subjected to heat treatment, documented with information on geographic origin, lighting conditions, field of view, photographer and published references.

A “ghost” fissure in a Sri Lankan sapphire treated with high-temperature heating plus pressure (HT+P). In parallel polars, the fissure shows transparent doubly refractive crystals. These have previously been identified as corundum by Lotus gemologists using microRaman. These tiny synthetic corundum crystals form during the treatment. FoV=4 mm.
A “ghost” fissure in a Sri Lankan sapphire treated with high-temperature heating plus pressure (HT+P). In light field illumination, the fissure shows low-relief crystals. FoV=4 mm.
Red pyrochlore crystals like this one, which was identified with microraman spectroscopy, are a common inclusion in basalt-related sapphire.
Heat treatment of this pink sapphire has caused small negative crystal inclusions to burst, creating shiny discoid fractures around the crystals.
Angular zoned chalky fluorescence like this is a tell-tale sign of heat treatment.
Angular zoned chalky fluorescence like this is a tell-tale sign of heat treatment.
Seeing the chalky hexagonal banding in shortwave UV light reveals that this sapphire from Burma was heated. Photo taken with M&A Instruments Deep-UV Fluorescence system.
Seeing the chalky hexagonal banding in shortwave UV light reveals that this sapphire from Burma was heated. Photo taken with M&A Instruments Deep-UV Fluorescence system.
Spall marks from heating on the pavilion of a heat-treated Kashmir (India) sapphire.
Small crystals with decolorized areas around growth tubes cut through on the surface. The growth tubes have apparently drawn titanium out of solid solution in the sapphire, thus cannibalizing the color.
Melted crystals with circular heat-induced “bubbly” fingerprints and partially dissolved silk in a heated sapphire from Sri Lanka; FOV 2 mm
Melted crystal with frozen bubble in sapphire. When a gem is heated, included crystals may melt and cool into a glass. Because the glass takes up less volume than the previous solid crystal, a contraction bubble forms in the glass; FOV ~2.5 mm

Heat treatment can alter inclusions and other internal features in sapphire. Changes may include modification or dissolution of rutile silk, alteration of mineral crystals, decrepitation of fluid inclusions, changes to healed fissures and the formation of heat-related features. Such evidence can be important in determining whether a sapphire has been heated.

Heated Sapphire Inclusion Photomicrographs

The Hyperion heated sapphire gallery includes microscopic features documented in heat-treated natural sapphires. Each entry is accompanied by descriptive information and, where available, references to the gemological literature.

What Inclusions Can Reveal About Heat Treatment

Microscopic examination is an important part of detecting heat treatment in sapphire. The condition of mineral inclusions, rutile silk, fissures and other internal features can provide evidence of exposure to elevated temperatures. These features are evaluated together with other gemological observations when determining treatment status.

Hyperion combines inclusion photomicrography with supporting gemological information so that heat-related features can be compared with documented examples in treated sapphires.

About Hyperion

Hyperion is the Lotus Gemology searchable inclusion database. It allows users to browse gemstone inclusions by gem type, geographic origin, treatment and keyword.

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