Sapphire Inclusions

First Published: 7 September 2026

Sapphire Inclusions

Explore sapphire inclusions in Hyperion, the Lotus Gemology inclusion database. Hyperion contains photomicrographs of inclusions and internal features in natural sapphire, documented with information on geographic origin, treatment, lighting conditions, field of view, photographer and published references.

Clouds of undissolved rutile silk decorate the inner world of this sapphire, providing evidence that the stone has not been subject to heat treatment. Specimen courtesy of Discovery Gems.
A “ghost” fissure in a Sri Lankan sapphire treated with high-temperature heating plus pressure (HT+P). In crossed 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. Nathan Renfro of the GIA was the first to notice these ghost crystals. E. Billie Hughes of Lotus Gemology was the first to identify them. FoV=4 mm.
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.
This sapphire was treated with heat at high temperatures, which melted its surfaces, creating the unusual appearance of recrystallized corundum on the surface.
These included hexagonal crystals have inclusions of their own. These are actually sapphire inclusions in sapphire, as shown by their extremely low relief.
These included hexagonal crystals have inclusions of their own. These are actually sapphire inclusions in sapphire, as shown by their extremely low relief. In darkfield they are hard to distinguish from the surrounding corundum, but in crossed polars it’s apparent that they are different crystals.
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.
This untreated Ceylon sapphire showed an unusual inclusion in the form of a small transparent crystal with two black grains embedded in it. Surrounding this was a flat fissure with a reddish color in transmitted light. It is possible that this is a zircon crystal with embedded uraninite and the reddish stain in the fissure is due to radiation from the zircon/uraninite.
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.

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Sapphire inclusions may include mineral crystals, rutile silk, healed fissures, fluid inclusions, negative crystals, color zoning and other features formed during or after crystal growth. Such features are important to gemologists because they can provide evidence useful in identifying sapphire, understanding its geological history, recognizing treatment and, in some cases, determining geographic origin.

Sapphire Inclusion Photomicrographs

The Hyperion sapphire gallery includes microscopic features found in sapphires from major deposits around the world. Each entry is accompanied by descriptive information and, where available, references to the gemological literature.

What Inclusions Can Reveal About Sapphire

Inclusions are an important part of sapphire identification. Their form, composition, orientation and alteration can help gemologists distinguish natural sapphire from synthetic material, recognize evidence of heat treatment, and study the geological environment in which the sapphire formed.

Hyperion combines inclusion photomicrography with supporting gemological information so that individual features can be compared with documented examples from known sapphire deposits.

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.