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.

These small irregular crystal grains were identified via micro Raman as anorthite feldspar.
This sapphire from Myanmar’s Mogok Stone Tract displays a classic fingerprint inclusion in a spider’s web shape. The plane of the inclusion is close to the basal plane. As a result, the healed areas have a hexagonal shape.
Another common guest mineral in sapphire is phlogopite mica, which is typically brown or orange in color. This example was identified as fluorapatite by micro Raman.
A common guest mineral in sapphire is apatite. These can take on a variety of forms, from rounded balls, such as that shown here, to hexagonal prisms and dog’s tooth shapes. This example was identified as fluorapatite by micro Raman.
Two small sapphires were submitted to Lotus Gemology for testing. Both were said to come from Kashmir (Sumjam, India). One of the stones had a small transparent crystal grain cut through on the surface, as shown in the center of this photo. Using micro Raman, we identified the inclusion as anorthite feldspar. Feldspars are common in Kashmir sapphire. On the other hand, apatite has not been reported in Kashmir sapphire, but it is common in Sri Lankan and Madagascar sapphires.
This yellow sapphire displays a striking angular, superficial chalky patch when viewed in shortwave UV illumination. This is the first time we have seen this reaction in a yellow sapphire that shows no signs of heat treatment, with all inclusions (intact negative crystals) and spectral information (strong 3160 in the infrared) pointing to an untreated gem. We have seen this reaction occasionally in untreated blue sapphires from Madagascar.
A superficial chalky patch is visible when this sapphire is viewed under shortwave UV illumination. While a chalky shortwave UV fluorescence is generally a strong indicator of heat treatment, on occasion we have seen these superficial patches in stones we believe to be untreated.
This hexagonal crystal with a metallic luster stood out in its sapphire host. Micro Raman analysis confirmed its identity as graphite.
This untreated pink sapphire from the Ilakaka area of Madagascar was part of a large parcel purchased from a miner by the author in 2005. It contains rounded zircon crystals, and blocky crystals, some with fringes. The crystal in the center was identified as muscovite mica by micro Raman.
This untreated pink sapphire from the Ilakaka area of Madagascar was part of a large parcel purchased from a miner by the author in 2005. It contains zoned clouds of fine rutile dust, rounded zircon crystals, and in the center, an irregular rounded crystal that was identified by micro Raman as anorthite, one of the end members of the plagioclase feldspar series.
Apatite is one of the most common inclusions in sapphire. Many appear as dogtooth shapes, such as this example in a Sri Lanka sapphire. It was identified using micro Raman.
This blocky white crystal was found breaking the surface in a pink sapphire from Madagascar’s Ilakaka region collected at the mines by Lotus Gemology’s Richard Hughes in 2005. Using our micro Raman unit to analyze it, we were pleasantly surprised to discover that it was andalusite. To the best of our knowledge, this is the first time andalusite has been discovered as an inclusion in corundum. Overhead lighting clearly shows the lower luster of the andalusite compared to the surrounding sapphire. This is because andalusite has an RI of 1.63, while corundum is 1.76.

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.

Search the Complete Hyperion Database