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.

Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form. On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. Solid carbon dioxide is what we know as “dry ice.” The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C.
Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form. On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. Solid carbon dioxide is what we know as “dry ice.” The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C.
Long, unbroken needles of undissolved rutile silk is a common feature in untreated Sri Lanka sapphire like this one.
This conical crystal displays interference colors when viewed in crossed polars.
This conical crystal displays interference colors when viewed in crossed polars.
Iridescent discoids are reminiscent of flower petals around tiny crystals in this basalt related sapphire.
Angular zoned chalky shortwave fluorescence provides evidence that this Madagascar sapphire was heated.
Angular zoned chalky shortwave fluorescence provides evidence that this Madagascar sapphire was heated.
A small black crystal peeks out from inside a negative crystal where it is held inside a Sri Lankan sapphire.
The angular chalky fluorescent patch in this sapphire provides evidence that the stone was heat treated.
This angular patch glows with a chalky appearance in shortwave UV light, providing evidence that the stone was heated.
In yellow sapphire from Chanthaburi, Thailand, a thin layer of iron-rich silk is typically found in green layers on the skin of the crystal. After cutting, it is commonly seen just under the table and/or culet.

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.