Exploring Gemstone Inclusions

After receiving a great question from one of our Facebook followers about gemstone inclusions, we decided to expand on the topic for everyone. Inclusions can get a bad rap, but often times they are useful to gemologists in differentiating a natural stone from a synthetic version.

A gemstone inclusion forms when a material gets trapped inside a mineral at any time during formation. It’s best to think of an inclusion as the gemstone’s unique fingerprint. Much like our own fingerprint, no two gemstones have the exact same characteristics.

Inclusions can take the form of other minerals, rocks, gas, or internal fractures caused during formation. Inclusions can even be insects or plants, frequently seen in amber.

inclusions
An octahedral diamond crystal inside of a diamond.

Inclusions can be placed in one of three categories: protogenetic (mineral particles that existed before the host crystal formed), syngenetic (particles that formed and grew alongside the host crystal), and epigenetic (inclusions that form after the host material stopped growing like stress cracks or damage by irradiation).

Inclusions are important when determining the value of a gemstone. For a diamond, the fewer inclusions, the rarer and more expensive. Too many inclusions can affect the overall appearance of a diamond. However, in a star sapphire, inclusions are what make the asterism phenomena (the star) possible. The presence of needle-like inclusions creates the beautiful six-rayed star pattern. Demantoid garnets are sometimes sought after for their inclusions, specifically the presence of the whispy, hair-like horsetail inclusion.

212-3547917_star sapphire
Star Sapphire

Inclusions also aid in determining the origin of a gemstone, as certain inclusion characteristics can sometimes be identified with a specific region. Synthetic stones can have inclusions too, but they are usually identified by the growth method used in a lab. Viewing and identifying an inclusion is best done by a microscope under controlled lighting conditions.

Sometimes jewelry owners can confuse an inclusion with crack or chip. It should be noted that Gem Shopping Network does not allow the sale of any gemstone with a crack, chip, or fracture. In addition, we don’t accept gemstones or diamonds with an inclusion that could cause an issue with the stability of the stone. If you have an inclusion in your stone, consider it a unique, identifying feature- much like freckles or a birthmark.

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