Although we usually focus on the outside of a gemstone when we are admiring a bejeweled piece of jewellery, the inside of a gemstone can tell us a lot. While it is obviously a lot easier to examine the inside of a gemstone when the gem is unset but it is still possible to do so with set gems. So what can an internal examination of a gemstone tell us? In most cases, it can help us identify the gemstone. It can also tell us if the gem is natural or not and whether a stone has been treated or not.

The inclusions inside a gem might include crystals, internal healed fractures, colour zoning (as in the sapphire in the photo at the top of the post) and growth planes. Some of these inclusions are diagnostic, that is, if they are inside a stone, they can identify a stone without question. Other inclusions may just indicate that a gem is natural while some might indicate a geographical location. Inclusions inside a gemstone can be quite desirable and looked for. That is not to say that the clarity of a stone is not important but rather that inclusions have important roles to play.

It is important to understand, too, that some gemstones are almost always included, like the emerald; others are usually included, like garnets, amethysts, sapphires and rubies: and others should not have inclusions but should be clear, like morganites and aquamarines.

Emeralds can contain extensive inclusions referred to as a ‘jardin’ or garden. Amethyst can contain healed internal fractures and goethite iron staining as well as ‘zebra stripes’ caused by liquid-filled inclusions:

And garnets can contain healed internal fractures and goethites as well:

I have talked in earlier posts about the beauty of inclusions inside moss agates and other quartzes. Inclusions really can tell us a lot about a gemstone.