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.

Fingerprints are made up of tiny negative crystals. This often contain carbon dioxide and were formed at depth under high pressure. When the gem reaches the surface, the pressure pushing out can be quite large. Thus they are particularly heat sensitive and often burst if the gem is heat treated. Here we can see what happens when such a fingerprint is subjected to heat treatment. Each tiny negative crystal bursts, creating a series of microfractures.
A small crystal with streams of particles coming off it in a heated Madagascar sapphire. Particle streams such as this form because an inclusion creates a barrier to growth behind it, resulting in the trapping of tiny fluid inclusions.
Many crystals contain shallow fissures on their surfaces. In sapphires from Sri Lanka, Myanmar and Madagascar, these fissures often contain yellow stains. High-temperature heating not only destroys the yellow stains, but begins a process of healing, where the fissures turn white and start forming fingerprints, as we can see here.
High-temperature heat treatment has the potential to alter certain types of solid inclusions. Here we see an included crystal that melted during heat treatment, turning into glass. Because a glass takes up less volume than a crystal, the result is a void, in the form of a bubble within the glass.
Pink sapphires from Sri Lanka are routinely heated at relatively low temperatures (>1200°C) to drive off the blue tint. While this rarely changes the inclusions, it can be unmasked by reference to the shortwave ultraviolet fluorescence, which often develops chalky zones, as shown in this stone.
An iridescent secondary fingerprint inclusion in a pink sapphire from Sri Lanka. The healing pattern reveals the underlying atomic symmetry. In this case, the hexagonal healing structure show that the fingerprint lies in the plane of the basal pinacoid.
When a rutile-silk containing sapphire (such as this stone from Kanchanaburi, Thailand) 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.
The yellow core of this Sri Lankan sapphire fluoresces orange when illuminated by a strong fiber-optic light.
Heat-altered “snowball” like crystals when viewed in transmitted light in a heat-treated sapphire from Sri Lanka.
The yellow core of this Sri Lankan sapphire will fluoresce orange when illuminated by a strong fiber-optic light.
Heat-altered “snowball” like crystals in a heat-treated sapphire from Sri Lanka.
A heat-altered fingerprint in a heat-treated sapphire from Sri Lanka.

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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.