Understanding Sapphire Inclusions: Nature's Fingerprints

Understanding Sapphire Inclusions: Nature's Fingerprints

Sapphires, like all gemstones, have been a subject of human admiration for centuries. They're particularly renowned for their stunning blue hues but come in almost every color of the rainbow (except red, as red sapphires are termed rubies). But beyond their beautiful shades, sapphires have a world inside of them: inclusions. These internal features can tell the story of a sapphire's geological journey. Let's delve into the various types of inclusions found within these stunning gemstones.

Needle Inclusions (Rutile Needles):

Also known as ‘silk,’ these slender, needle-like inclusions are composed of rutile. They can appear as singular needles or as clusters, giving the stone a silky appearance when viewed under the light. In some cases, they can enhance the value of the sapphire by creating phenomena like asterism (star effect) or cat’s eye.

Photo taken of our blue sapphire

Crystal Inclusions:

Sapphires can sometimes have other minerals trapped inside them during their formation. These tiny mineral crystals can be of the same mineral or different ones, like garnet, zircon, or calcite. The presence, size, and arrangement of these crystals can significantly influence the gem's clarity grade.

Photo taken of our blue sapphire

Feather Inclusions:

Feathers are small fractures within the sapphire that can look like wisps or clouds. They are often not visible to the naked eye and usually require magnification to be identified. In some cases, if the feather reaches the surface of the sapphire, it can pose durability issues.

Photo taken from Lotus gemology

Cavities and Growth Tubes:

These are hollow channels or tubes that can be seen inside the sapphire. Growth tubes can be long and slender or short and wide. They sometimes contain remnants of the solution from which the sapphire crystallized.

Photo taken from lotus gemology

Fingerprint Inclusions:

These are a series of tiny fluid-filled or gas-filled cavities that resemble the patterns of a fingerprint. They are usually formed when the sapphire undergoes healing post a fracture.

Photo taken of our blue sapphire

Color Zoning:

Color zoning refers to areas of different color tones or saturation in a sapphire. It's a result of uneven distribution of trace elements during the gem's formation. When present, one can notice bands, spots, or patches of different color intensity within the gem.



Some sapphires can show areas where the crystal lattice orientation changes, indicating that two crystals grew together. This phenomenon is termed twinning. Twinning planes can sometimes be seen as fine lines or striations inside the gem.

Photo taken from Lotus gemology


Inclusions in sapphires, or any other gemstones, are like fingerprints – each one is unique and tells a story. While the presence of inclusions often dictates the quality and value of the gemstone, they also provide insight into its history and formation. The inclusions allow us to know the origin of the stone and if there is any treatment done to the gemstone. In many cases, inclusions can enhance the beauty and individuality of a gem, making it truly one-of-a-kind. Most sapphires would also come with a combination of different inclusions. As with all gemstones, the art is in finding the balance between the beauty brought by inclusions and the overall clarity and quality of the gem. 

Check out our wide range of Sapphire gemstones!

Photo by Lotus Gemology- A negative crystal, surrounded by iridescent fingerprints. 

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