Treated Sapphire Inclusions

First Published: 7 September 2026

Treated Sapphire Inclusions

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

When a fingerprint is heated, the tiny negative crystals that form the fingerprint burst, creating tiny microfractures to release the pressure. This often creates a somewhat frosted appearance, as one can see here.
“Bubbly” melted crystals in a heat-treated sapphire from Sri Lanka.
A heat-induced discoid inclusion in a heat-treated sapphire from Sri Lanka.
When a silky sapphire is heated to a high enough temperature, titanium from the rutile silk is forced into solid solution, coloring the stone blue. But the silk may also contain other elements that cannot dissolve into sapphire so readily, leaving behind silk “skeletons,” as shown here.
Nigeria sapphire; heated; crystal of what is probably rutile breaking the surface
An orange rutile crystal polished through the surface of this sapphire from Nigeria.
Many gems entering the market from Burma have been found to be oiled in an attempt to conceal their fissures. In transmitted light, the trapped air bubbles within the oil-filled fissures appear in high relief rounded patches. If the hot point is stroked against the surface, when the temperature is sufficiently raised, the trapped air bubbles will expand and contact as the hot point move closer or farther from them.
This untreated Burmese sapphire displays a fingerprint made up of well-formed negative crystals. Because high-temperature heat treatment will generally damage such cavities, undamaged negative crystals are strong evidence of the lack of high-temperature heat treatment.
Certain type of solid inclusions are heat sensitive and may alter when the gem is heat treated. Here we see crystals that have altered into “snowball” like forms. In addition, the coefficient of thermal expansion of the included crystals was greater than corundum. Thus when heated, they expanded more than the surrounding sapphire, producing glassy discoid fissures.
High-temperature heat treatment has the potential to alter certain types of solid inclusions. Here we see an included crystal that melted during heat treatment, turning into glass. Because a glass takes up less volume than a crystal, the result is a void, in the form of a bubble within the glass.
Heat-altered “snowball” like crystals in a heat-treated sapphire from Sri Lanka.
Heat-altered fingerprints in a heat-treated Ceylon sapphire. Close examination reveals microscopic fractures around each negative crystal, due to the heat treatment.

Treatment can alter existing inclusions and produce new microscopic features in sapphire. These may include changes to mineral inclusions, altered rutile silk, tension fractures, healed fissures, residues and other features associated with heating, diffusion, fissure filling and other treatment processes.

Treated Sapphire Inclusion Photomicrographs

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

What Inclusions Can Reveal About Sapphire Treatment

Microscopic examination is an important part of detecting treatment in sapphire. The appearance and alteration of inclusions, fractures and growth features can provide evidence of treatment and, in some cases, information about the processes to which a sapphire has been subjected.

Hyperion combines inclusion photomicrography with supporting gemological information so that treatment-related features can be compared with documented examples in natural sapphire.

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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