Treated Sapphire Inclusions

First Published: 7 September 2026

Treated Sapphire Inclusions

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

Internal diffusion is visible in this heat-treated blue sapphire from Sri Lanka.
Sharp angular growth zoning in a heat-treated yellow sapphire from Sri Lanka.
When Sri Lankan yellow sapphires with exsolved particles are heat treated, magnesium exits the particles and creates yellow-producing trapped-hole color centers. The result is color concentration around the particles, a process termed “internal diffusion” by gemologist, John Koivula.
When Sri Lankan yellow sapphires with exsolved particles are heat treated, magnesium exits the particles and creates yellow-producing trapped-hole color centers. The result is color concentration around the particles, a process termed “internal diffusion” by gemologist, John Koivula.
Low iron rubies (and pink and padparadscha sapphires) from localities like Mogok, Mong Hsu (Myanmar) and Sri Lanka will often display chalky zones in short wave ultraviolet after heat treatment. Here we see an excellent example in a heat-treated padparadscha sapphire from Sri Lanka. This fluorescence is positive proof of heat treatment.
Crossing twin planes in a sapphire from a basaltic source. These are secondary glide twins, created by pressure after the stone grew, and form parallel to the rhombohedron faces, intersecting at 86.1 and 93.9°.
A brilliantly iridescent fingerprint in a sapphire from Sri Lanka. Such healing patterns reveal the underlying atomic symmetry. In this case, the rectangular healing pattern shows that this fingerprint lies parallel to a prism face.
Certain type of solid inclusions are heat sensitive and may alter when the gem is heat treated. Here we see crystals that have altered into “snowball” like forms. In addition, the coefficient of thermal expansion of the included crystals was greater than corundum. Thus when heated, they expanded more than the surrounding sapphire, producing glassy discoid fissures.
When a rutile-silk containing sapphire (such as this stone from Nigeria) is heated, the titanium from the rutile moves into solid solution in the sapphire, coloring the area around the rutile blue, creating a distinctive “ink spot” internal diffusion pattern.
When low-iron sapphires are heat treated, a chalky shortwave fluorescence often develops. This generally is related to colorless or lightly colored regions of the gem, and so follows the crystallographic structure, as is seen here. This is strong evidence of heat treatment.
When a rutile-silk containing sapphire (such as this stone from Sri Lanka) is heated, the titanium from the rutile moves into solid solution in the sapphire, coloring the area around the rutile blue, creating a distinctive “ink spot” internal diffusion pattern.
When a rutile-silk containing sapphire (such as this stone from Sri Lanka) is heated, the titanium from the rutile moves into solid solution in the sapphire, coloring the area around the rutile blue, creating a distinctive “ink spot” internal diffusion pattern.

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Treatment can alter existing inclusions and produce new microscopic features in sapphire. These may include changes to mineral inclusions, altered rutile silk, tension fractures, healed fissures, residues and other features associated with heating, diffusion, fissure filling and other treatment processes.

Treated Sapphire Inclusion Photomicrographs

The Hyperion treated sapphire gallery includes microscopic features documented in natural sapphires subjected to treatment. Each entry identifies the recorded treatment and is accompanied by descriptive information and, where available, references to the gemological literature.

What Inclusions Can Reveal About Sapphire Treatment

Microscopic examination is an important part of detecting treatment in sapphire. The appearance and alteration of inclusions, fractures and growth features can provide evidence of treatment and, in some cases, information about the processes to which a sapphire has been subjected.

Hyperion combines inclusion photomicrography with supporting gemological information so that treatment-related features can be compared with documented examples in natural sapphire.

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.