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.

This hexagonal crystal with a metallic luster stood out in its sapphire host. Micro Raman analysis confirmed its identity as graphite.
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.
Basal parting seen on the back of a black star sapphire from Chanthaburi, Thailand. Note the step-like appearance. Basal parting in these stones is due to exsolution of hematite/ilmenite silk, which produces both the star effect and a lack adhesion.
A small rhombohedral parting plane on the girdle of a black star sapphire from Chanthaburi, Thailand. This parting is cause by exsolution of boehmite, which produces a lack of adhesion.
Basal parting seen on the back of a black star sapphire from Chanthaburi, Thailand. Note the step-like appearance. The two diagonal lines are rhombohedral parting planes. Basal parting in these stones is due to exsolution of hematite/ilmenite silk, which produces both the star effect and a lack adhesion.
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.
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.
This black star sapphire had large pits on the base filled with dopping varnish. Following removal of the varnish by soaking in alcohol, the 75-ct stone lost about 0.25 ct of weight. But careful examination after the varnish removal revealed something far more sinister, a layer of glass coating the inside of the cavities. In addition, we could see the the glass extended across much of the base, as clearly revealed after immersing the gem in di-iodomethane.
This black star sapphire had large pits on the base filled with dopping varnish. Following removal of the varnish by soaking in alcohol, the 75-ct stone lost about 0.25 ct of weight. But careful examination after the varnish removal revealed something far more sinister, a layer of glass coating the inside of the cavities. Note the perfectly smooth curved cavity surfaces, nothing like what one would expect for the broken surface of sapphire. In addition, we could see the the glass extended across much of the base.
This black star sapphire from Chanthaburi, Thailand has large pits on the base filled with a brown dopping varnish. Long wave ultraviolet light shows the varnish fluoresces orange. Note the pits on the surface of the varnish where gas bubbles were cut through.
This black star sapphire from Chanthaburi, Thailand has large pits on the base filled with a brown dopping varnish. Long wave ultraviolet light shows the varnish fluoresces orange.

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.