euhedral spinel inclusionseuhedral spinel inclusions

Spinel Inclusions

The materials trapped inside gems hold a wealth of information. Learn what the most common types of spinel inclusions reveal about this gem.

6 Minute Read

euhedral spinel inclusions
The octahedral inclusion in this cobalt spinel is a euhedral crystal. That means it has a regular, distinct crystal shape and well-formed faces. It also reflects the spinel’s octahedral crystal structure. Natural spinel, Sri Lanka. Photo by E. Billie Hughes. © Lotus Gemology. Used with permission.

The Importance of Inclusions in Gemology

Although a few gems contain beautiful inclusions visible to the naked eye, you’ll need a loupe or microscope to view inclusions in most gemstones, including spinels.

In general, inclusions can help answer many questions about their host gemstones. First and foremost, inclusions might provide clues for identifying a gemstone’s species. They may also help gemologists determine whether a particular specimen is natural or synthetic. In some cases, that may even indicate the source. Inclusions might also divulge if the host gem has received treatment or enhancement.

Natural Spinel Inclusions

The GIA classifies spinels as Type II clarity gemstones, which means they’re usually included. Although the highest-valued spinels are usually eye-clean, most spinels contain many kinds of inclusions visible only through magnification and some visible to the naked eye.

sugarloaf cabochon spinel with eye-visible inclusions
Sugarloaf cabochon-cut spinel with eye-visible inclusions. 4.17 cts, 9.9 x 8.9 mm, Sri Lanka. ©

Emily Frontiere

Emily Frontiere is a GIA Graduate Gemologist. She is particularly experienced working with estate/antique jewelry.

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