Natural Ruby Inclusions

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

A heat-altered crystal with an iridescent decrepitation halo, alongside a surface cavity filled with glass.
Patches of glass on the surface of a heat-treated ruby from the Thai/Cambodian border region.
Heat-altered crystals with decrepitation halos in the basal plane.
Iridescent fingerprint in a ruby from the Thai/Cambodian border.
Rose channels in Thai/Cambodian ruby. These are often confused with rutile silk in corundum, but they are easily distinguished as they run in entirely different crystallographic directions. Rutile silk unmixes in three intersecting directions (60/120°) parallel to the faces of the hexagonal prism in the plane of the basal pinacoid (90° to the c-axis). In contrast, Rose channels form parallel to the edges of the rhombohedron, in three directions, but only two in the same place, oblique to the c-axis. They intersect at 86.1/93.9°.
The star imprisoned in the heart of this asterated ruby from Sri Lanka is due to tiny crystals of rutile formed through a process of exsolution, where excess titanium was squeezed out of solution. Unable to grow freely, it was constrained by the host corundum structure, forced to crystallize in three directions in the host’s basal plane. The result is simple magic—a magnificent star—yet another wonder that is the microworld of gemstones.
When Burmese rubies, such as this stone from Mong Hsu, are heat treated, they often develop a zoned chalky fluorescence in shortwave UV. In this position, the stone’s original blue core has been removed by the heat treatment, but that zone does not display the chalky fluorescence, just fluorescing red.
When Burmese rubies, such as this stone from Mong Hsu, are heat treated, they often develop a zoned chalky fluorescence in shortwave UV.
When a ruby is heat-treated at a high enough temperature, the angular channels of fingerprints begin a “necking down” process where they become more rounded, as seen here. This is particularly true if fluxes are used during the treatment.
The vast majority of Mong Hsu rubies are heated with fluxes to heal their fissures. This is a rare example of a fingerprint in an Mong Hsu ruby that has not been heated. Note the angular nature of the negative crystals. Overhead lighting was used to reveal the interference colors on the surface of the liquid-filled channels.
The vast majority of Mong Hsu rubies are heated with fluxes to heal their fissures. This is a rare example of a fingerprint in an Mong Hsu ruby that has not been heated. Note the angular nature of the negative crystals and the two-phase fillings.
These disruption cracks are shallow fissures that form as a result of rapid polishing.

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Natural ruby 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 ruby, understanding its geological history, recognizing treatment and, in some cases, determining geographic origin.

Natural Ruby Inclusion Photomicrographs

The Hyperion natural ruby gallery includes microscopic features found in rubies 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 Natural Ruby

Inclusions are an important part of ruby identification. Their form, composition, orientation and alteration can help gemologists distinguish natural ruby from synthetic material, recognize evidence of heat treatment, and study the geological environment in which the ruby formed.

Hyperion combines inclusion photomicrography with supporting gemological information so that individual features can be compared with documented examples from known ruby 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.