Inner Worlds

Inclusions in the form of liquids, gases or solid materials are trapped at any time inside the evolving mineral. Under some special circumstances, mostly due to a change in pressure or temperature, they can also form or infiltrate the mineral after it has formed. Other characteristic inclusions emerge even later during various treatments and thus help gemmologists identify such alterations of the stone. Solid inclusions are divided into three different kinds. Protogenetic inclusions are minerals that have formed before the host crystal. They are trapped during the long process of the gemstone’s crystallisation. Often, different minerals form under the same conditions and at the same time. They can be found included in one another and are therefore syngenetic inclusions. Due to different circumstances, like changes in the environment of a gemstone, some solid inclusions even form after the host crystal. These epigenetic inclusions mostly form within fractures of the host mineral and tend therefore to consist of flat crystals that are visually distinct from the rather well-formed syngenetic inclusions. 

The so-called "three-phase inclusions", as seen below, consist of gas bubbles, liquids and crystalline structures which were all trapped within the growing gemstone. These inclusions are typical in emeralds from Colombia. They often begin as purely fluid inclusions of a salty liquid during the birth of the host mineral. When the crystal cools down to near-surface temperature, minerals and gases separate from the fluid thus forming these intricate patterns.

Delicate inclusions, such as pargasite needles, fine dust clouds and crossing dust-tracks can help identify the origin of a sapphire. Although these inclusions can appear in stones from Kashmir, Sri Lanka or Madagascar, precise observations can reveal subtle differences in their pattern and help identifying the gemstone’s origin. This picture shows a precious pargasite crystal inclusion in a magnificent sapphire from Kashmir.