Inclusion
Definition
Any internal characteristic within a gemstone — such as crystals, feathers, clouds, needles, or cavities — that formed during the stone's growth. Inclusions affect clarity grading and value.
Inclusions are natural features trapped inside a gemstone during its formation millions of years ago. They include mineral crystals (solid inclusions), fractures (feathers), liquid-filled cavities, growth lines, twinning, and needle-like rutile silk. In diamonds, inclusions are graded on the GIA clarity scale from Flawless (FL) to Included (I3). While inclusions generally reduce a stone's value, they serve important functions: they prove natural origin (vs synthetic), help identify gemstone species, and can create desirable optical effects like asterism in star sapphires or horsetail patterns in demantoid garnet. In emerald, inclusions are so expected that the French term 'jardin' (garden) describes them. The goal for most buyers is 'eye-clean' — no inclusions visible to the naked eye at normal viewing distance.
Usage in the Trade
Inclusions are a primary factor in gemstone grading, pricing, and identification. They are discussed in lab reports, appraisals, and buying decisions for all transparent gemstones.
Related Resources
Related Terms
Related Gemstones
Diamond
The hardest natural substance and the benchmark of the gemstone world.
Emerald
The green jewel of royalty, prized for its saturated color above all else.
Ruby
The king of colored gemstones, valued for its vivid red brilliance.
Sapphire
Corundum in every color except red — the most versatile precious stone.