Sapphire Inclusions

First Published: 7 September 2026

Sapphire Inclusions

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

Angular zoned chalky fluorescence like this is a tell-tale sign of heat treatment.
Feldspar crystals are a frequent guest of sapphires derived from basalt deposits. Thus it was no surprise when the three larger crystals show here turned out to be feldspar. The identification was made with Lotus Gemology’s micro Raman unit. Examination with crossed polars reveals the doubly refractive nature of the feldspar guest inclusions.
A glassy discoid around a tiny melted crystal provides evidence that this inclusion’s sapphire host has been heated. Specimen courtesy Tristan Knowles.
An elongated crystal in this sapphire was identified as grandidierite with micro Raman. Here in crossed polars we can see it display rainbow interference colors.
An elongated crystal in this sapphire was identified as grandidierite with micro Raman.
This padparadscha sapphire from Sri Lanka displayed unusual ghost crystals, several of which were cut through on the surface. In reflected light at the surface, they were detectable only by the inclusions in the crystals themselves, showing no difference in luster from the surrounding sapphire, but stood out brilliantly between crossed polars. This identified them as corundum in corundum. Edward Gübelin first identified corundum in corundum in 1940.
Red pyrochlore crystals like this one, which was identified with microraman spectroscopy, are a common inclusion in basalt-related sapphire.
Gems in gems. When we saw this green crystal inside a blue sapphire from Sri Lanka, we were curious what material it could be. Micro raman analysis confirmed that it is a green spinel.
Orange staining stands out against the body color of this blue sapphire. If a stone like this is heated, the staining is likely to turn a darker reddish color.
Iron-rich silk with a “hairy” appearance lights up the interior of this sapphire.
In this negative crystal within an untreated Sri Lanka padparadscha, one can see a high-relief hexagonal plate of graphite, along with a needle of diaspore. The undamaged nature of the negative crystal and diaspore needle confirms that the gem has not been heat treated.
In this negative crystal within an untreated Sri Lanka padparadscha, one can see a hexagonal plate of graphite, along with a needle of diaspore. The undamaged nature of the negative crystal and diaspore needle confirms that the gem has not been heat treated.

Search the Complete Hyperion Database

Sapphire 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 sapphire, understanding its geological history, recognizing treatment and, in some cases, determining geographic origin.

Sapphire Inclusion Photomicrographs

The Hyperion sapphire gallery includes microscopic features found in sapphires 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 Sapphire

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

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