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.

A euhedral birefringent crystal floats against a canvas of rutile silk in this untreated sapphire from Sri Lanka.
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.
Internal diffusion in heat-treated Ceylon sapphire. This is caused by the bleeding of titanium into the surrounding sapphire from titanium-bearing inclusions such as rutile during high-temperature heat treatment.
Fingerprints are actually networks of tiny negative crystals produced by the healing of a fissure. This is a classic example in a Kashmir sapphire.
Fingerprints are actually networks of tiny negative crystals produced by the healing of a fissure. This is a classic example in a Kashmir sapphire.
One of the classic inclusions of sapphires is negative crystals. This one features a large CO2 and provides proof that the gem has not been heat treated. The heat of the microscope bulb is often enough to cause these bubbles to disappear. Cooling the specimen brings them back.
Crystals of what are probably apatite in a heated bi-color sapphire from Sri Lanka.
A superb fixed star is seen in this trapiche sapphire from Mogok, Burma.
Negative crystals seeking the surface in this natural Sri Lanka sapphire. In many cases, negative crystals cannot withstand high-temperature heating and so when they are found in an undamaged state, represent strong indications that the gem has not undergone heat treatment.
Undissolved rutile silk in a sapphire from Burma’s Mogok Stone Tract. Rutile silk in corundum forms in three directions at 60/120° in the plane of the basal pinacoid (perpendicular to the c axis).
Irregular inclusions of unknown nature lying in the basal plane are seen in reflected light within this heat-treated Sri Lanka sapphire. These have sometimes been associated with beryllium diffusion, but are not diagnostic for it.

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.