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.

Primary rutile crystals caught amidst secondary rutile silk in this sapphire from Sri Lanka.
Looking like a pistol, a group of three primary rutile crystals sits against a background of secondary rutile silk in this sapphire from Sri Lanka.
A brilliantly iridescent fingerprint in a sapphire from Sri Lanka. Such healing patterns reveal the underlying atomic symmetry. In this case, the rectangular healing pattern shows that this fingerprint lies parallel to a prism face.
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.
When a rutile-silk containing sapphire (such as this stone from Nigeria) is heated, the titanium from the rutile moves into solid solution in the sapphire, coloring the area around the rutile blue, creating a distinctive “ink spot” internal diffusion pattern.
An iridescent secondary fingerprint inclusion in a pink sapphire from Sri Lanka. The healing pattern reveals the underlying atomic symmetry. In this case, the rectangular healing structure show that the fingerprint lies in the plane of the hexagonal prism (parallel to the c axis).
When low-iron sapphires are heat treated, a chalky shortwave fluorescence often develops. This generally is related to colorless or lightly colored regions of the gem, and so follows the crystallographic structure, as is seen here. This is strong evidence of heat treatment.
When a rutile-silk containing sapphire (such as this stone from Sri Lanka) is heated, the titanium from the rutile moves into solid solution in the sapphire, coloring the area around the rutile blue, creating a distinctive “ink spot” internal diffusion pattern.
When a rutile-silk containing sapphire (such as this stone from Sri Lanka) is heated, the titanium from the rutile moves into solid solution in the sapphire, coloring the area around the rutile blue, creating a distinctive “ink spot” internal diffusion pattern.
Fingerprints are made up of tiny negative crystals. This often contain carbon dioxide and were formed at depth under high pressure. When the gem reaches the surface, the pressure pushing out can be quite large. Thus they are particularly heat sensitive and often burst if the gem is heat treated. Here we can see what happens when such a fingerprint is subjected to heat treatment. Each tiny negative crystal bursts, creating a series of microfractures.
A small crystal with streams of particles coming off it in a heated Madagascar sapphire. Particle streams such as this form because an inclusion creates a barrier to growth behind it, resulting in the trapping of tiny fluid inclusions.
Many crystals contain shallow fissures on their surfaces. In sapphires from Sri Lanka, Myanmar and Madagascar, these fissures often contain yellow stains. High-temperature heating not only destroys the yellow stains, but begins a process of healing, where the fissures turn white and start forming fingerprints, as we can see here.

Search the Complete Hyperion Database

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.