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 mica crystal with a lovely “rosette” surrounding it graces the interior of this untreated Mozambique ruby from the Montepuez area.
This Mozambique ruby has been heat treated, causing an included crystal to melt. The resulting glass occupies less space than the previous crystal, resulting in a frozen gas bubble.
Included crystals in a ruby from Montepuez, Mozambique.
A small heat-altered fingerprint in an unusual, beryllium-treated ruby.
When a gem is heat treated, solid inclusions may melt. This photo illustrates two different examples. In the foreground a crystal has melted and cooled into a glass. Because the glass takes up less volume than the earlier crystal, the difference results in a bubble in the glass. Looking further in the background we can see small blue dots. These are the remnants of rutile silk. Heat treatment alters the rutile, sending titanium into solid solution in the corundum. The result is blue “ink spots” surrounding the partially dissolved rutile.
Shortwave ultraviolet can often reveal heat treatment even at relatively low temperatures. Low-iron rubies, padparadschas and blue sapphires will often display a zoned chalky fluorescence following heat treatment. It is generally the colorless areas of the stone that show this. The presence of chalky SW fluorescence is a strong indication of heat treatment.
Shortwave ultraviolet can often reveal heat treatment even at relatively low temperatures. Low-iron rubies, padparadschas and blue sapphires will often display a zoned chalky fluorescence following heat treatment. It is generally the colorless areas of the stone that show this. The presence of chalky SW fluorescence is a strong indication of heat treatment.
Mozambique rubies are recovered from an iron-rich soil, which stains the surface-reaching fissures orange. Heat treatment at just 350°C converts the yellowish limonite, which consists of α-FeO(OH), to reddish hematite, which consists of α-Fe2O3. Unfortunately the strong body color of ruby makes it impossible to see this conversion by color alone, but micro-Raman spectroscopy can sometimes detect the change. Heat treatment also causes these naturally-stained fissures to become white and even begin healing into fingerprints.
This small yellowish crystal in a Thai/Cambodian ruby offers proof that the stone has not been subjected to heat treatment. After heating, the crystal would melt into a glass.
This small yellowish crystal in a Thai/Cambodian ruby offers proof that the stone has not been subjected to heat treatment. After heating, the crystal would melt into a glass.
A winged mica crystal within a ruby from Montepuez, Mozambique. These inclusions are heat sensitive and often develop glassy tension fissures around them following heat treatment.
Amphibole rods are a common guest in Montepuez (Mozambique) rubies and are unaffected by low-temperature heat treatment.

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.

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