Inclusions in Gems, a view of the inner world of gemstones


A view of the inner world of gemstones

"Three phase" inclusions

“Three phase” inclusions in a emerald

The inner world of gems is fascinating. Inclusions found within gems are the things that get gemmologists hooked on this science. We love to look at the fascinating crystals, growth features and strange structures in gems. Many inclusions are crystals of minerals.


An emerald may be identified as natural if it has three-phase inclusions (a solid, a liquid and a gas; with the solid being a crystal of some kind, and the gas being a bubble that sometimes can move around in the liquid). Emeralds originating from Colombia are particularly noted for three-phase inclusions.


Diamonds can have lots of interesting inclusions, sometimes another diamond inside a diamond, but often a crystal of an entirely different mineral. We often see reddish garnet crystals in diamonds.

Diamond  with bright red inclusions 5

Diamond with bright red garnet inclusions

Sometimes we might see several different colours of inclusion in the same diamond. This one has an inclusion of garnet that is orange brown colour and another that is green and is possibly diopside:

Diamond 0.33ct orange brown and green crystals

Diamond with orange-brown garnet, and green (possibly diopside) crystal inclusions

Sometimes we don’t know what an inclusion is, being inside another gem makes it hard to get at, and complex to test, but it’s still really interesting to look at. This orangish inclusion in the corner of a diamond looks a bit like a lighthouse floating in space, or a Dalek (ask a Doctor Who fan). It isn’t either of those things, it’s a mineral, however, we’re not sure what that mineral is.

Diamond inclusion hexagonal crystal pinkish brown (9)

Pinkish brown crystal inclusion in a diamond

There are naturally occurring fractures in gems, they are often called “feathers”. I guess the reason for calling them “feathers” is because they can sometimes look like that. This one in a diamond really looks like a feather:

Diamond inclusion feather incident light

“Feather” in a diamond


Sometimes we see inclusions of one colour mineral in another colour of gem. Here is a red crystal of a mineral called rutile in a blue sapphire. If it is placed just right (or wrong) the colours can combine to create a new colour to the eye (more purplish, in this case, with red mixed with the very nice blue)

Corundum sapphire with red crystal inclusion no heat 8

Blue sapphire with a red rutile crystal inclusion

Emeralds can have some very interesting inclusions, apart from three-phase ones. Here we have opaque cube shaped yellow metallic pyrite inclusions that are of a size that can be seen with the naked eye. Emeralds usually have eye-visible inclusions of some kind.

Beryl emerald with pyrite inclusions 8 copy

Emerald with pyrite cube crystal inclusions


Among the most commonly seen gems in the world are those of the quartz family. There are so many varieties, colours and textures of quartz found all around the world, and each can have distinctive inclusions. Often, quartz is a modestly priced gem, and specimens with noticeable and desirable inclusions are often available. This example of “rock crystal” quartz features dark reddish-black needle-like inclusions, scattered like pick-up-sticks.

Quartz rock crystal with orangish brown needle inclusions 2

Rock crystal quartz with scattered needle-like tourmaline crystals

Inclusions are such an interesting feature of gems, and for any gemmologist with a microscope or a loupe, they’re among of the most fascinating features of a gem. While most people tend to think of inclusions in a negative way, they make gems unique, and give each its own fingerprint, providing hours of distraction for a gemologist, or anyone else.




About Duncan Parker

Duncan Parker, FGA, FCGmA, CAP (CJA), Vice President. Duncan is a columnist and contributor for industry magazines and journals. He has been an instructor of the gemstone course at Ryerson University, the Gemmology courses of George Brown College and Canadian Gemmological Association as well as instructor Master Valuer Program with the Canadian Jewellers Association. A renowned expert, he speaks regularly at international gem and jewellery conferences and symposiums, as well as at less formal events. He has served as President of the Canadian Gemmological Association since 1995. Before joining Dupuis Auctioneers, Duncan was a director of research at Harold Weinstein Ltd., a leading and respected jewellery appraisal company.
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