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.

Demonstrating that the inner world can be as captivating as that outside, this Madagascar sapphire displays a small fingerprint scar with a beguiling moiré pattern. The undamaged nature of this inclusion testifies to the natural, untreated origin of the gem.
The concept of chromophore cannibalization is clearly illustrated in this photomicrograph of an untreated Madagascar sapphire. When zoned clouds of tiny exsolved inclusions are seen in transmitted light, they are found to be in decolorized areas, while blue areas are cloud free. The reason is that the tiny particles sucked titanium atoms out of solution, “cannibalizing” these potential chromophores.
Madagascar sapphires often contain zircon crystals. More typically we see them in rounded, oval forms, but occasionally we find an example of a blocky zircon crystal like this one.
When viewed in lightfield, it can be hard to tell a crystal from a negative crystal, as they have a similar appearance.
When crystals are viewed in crossed polars, it becomes easy to distinguish birefringent crystals from those that are singly refractive or are negative crystals.
An irregular crystal displays its birefringent nature when viewed in crossed polars.
Some time after this Sri Lankan sapphire crystal grew, a fissure developed. Slowly the fissure healed shut, trapping liquid and gaseous carbon dioxide in this fanciful pattern of inward-facing crystal faces which we term negative crystals. When viewed with overhead lighting, this ancient scar lights up in a cascade of color. The symmetry of these voids mimics the underlying crystallographic symmetry of the sapphire because these are simply inward looking faces.
An opaque crystal, likely iron sulphide, creates a striking image in this untreated Sri Lankan sapphire.
Uraninite crystals with small halos seem to float across this untreated sapphire.
A beautiful iridescent fingerprint shines in this untreated Sri Lanka sapphire.
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.

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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.