Treated Spinel Inclusions

First Published: 7 September 2026

Treated Spinel Inclusions

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

A large negative crystal with a mobile gas bubble resides in this unheated Burmese spinel. Analyses with microRaman spectroscopy were inconclusive. However, a near-invisible fissure extends through this negative crystal to the surface. By using a hot point, oil leaked out of this fissure and others around the stone. Therefore, the cavity may be filled with oil.
Within this heated red spinel from the Mahenge region of Tanzania, lies a large crystal (possibly apatite or a carbonate) that exhibits signs of heat damage, specifically the frosted appearance; attached to the crystal is an iridescent plane of thin-films. Additionally, fine remnants of partially dissolved silk (likely högbomite) are scattered across the stone.
The heat treatment of spinel is quite rare, but not unknown and most of the stones are of a purplish red color. Here we see heat-damaged crystals in a Burma spinel. The best way to identify heat treatment in spinel is generally via the photoluminescence (PL) spectrum, rather than inclusions.
When a gem is heated, it and everything contained in it expands, governed by each material’s coefficient of thermal expansion. Should an included crystal expand more than the host, the result is a tension fissure, such as this around a heated apatite crystal in Burma red spinel.
While still rare in the market, some spinels are heat treated. We identified that this stone was heated through a combination of the PL (photoluminescence) spectrum and the inclusions, which show signs of melting.
While still rare in the market, some spinels are heat treated. We identified that this stone was heated through a combination of the PL (photoluminescence) spectrum and the inclusions. In this case, the dotted planes that we see may be remnants of the oriented lamellae sometimes seen in Tanzanian spinel.
A gas bubble floats inside this cavity in a spinel from Burma. To date, we have not been able to verify whether this is a natural or man-made feature. Specimen courtesy Gil Yuda.
This spinel was treated with cobalt diffusion. Signs of the treatment can be seen in the drippy appearance of the fingerprint and slightly melted, rounded edges of the crystal seen here.
The bright, glassy discoid depicted here provides evidence that its spinel host was heated. Raman spectroscopy confirmed this suspicion.
Two solid crystals of unknown identity perch inside this red spinel from Myanmar’s Mogok Stone Tract.
This red spinel from Tanzania’s Mahenge mines showed an unusual orange coloration surrounding a fingerprint inclusion. But when examined in oblique fiber-optic lighting, the orange area displayed milky bluish clouds. This unmasked the orange color as a function of scattering, the same phenomena that creates a blue sky and orange sunset.
This red spinel from Tanzania’s Mahenge mines showed an unusual orange coloration surrounding a fingerprint inclusion. But when examined in oblique fiber-optic lighting, the orange area displayed milky bluish clouds. This unmasked the orange color as a function of scattering, the same phenomena that creates a blue sky and orange sunset.

Treatment can alter existing inclusions and produce new microscopic features in spinel. These may include changes to mineral inclusions, tension fractures, healed fissures, residues and other features associated with heating and other treatment processes.

Treated Spinel Inclusion Photomicrographs

The Hyperion treated spinel gallery includes microscopic features documented in natural spinels 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 Spinel Treatment

Microscopic examination is an important part of detecting treatment in spinel. 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 spinel has been subjected.

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

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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