All minerals have inclusions. Usually these are other minerals or cavities filled with gas or liquid. And sometime we should use loupe or microscope to find it. Inclusions are of great importance for gemologists. With the help of them, they can understand the origin of the stone, its authenticity and refinement. Some inclusions give the stone individual effects: for example, cat's eye or asterism. Inclusions have attracted human attention since ancient times, for example, thanks to the insects in amber, people were able to understand that the amber is fossilized tree resin. Inclusions are also used to understand the formation of mineral conditions. We can find out such conditions of mineral formation as: temperature, pressure, density, chemical composition of the rock, geological age. Emeralds from mica-rich rocks called schists, such as Russian emeralds, often contain mica inclusions. On the other hand, emeralds from the hydrothermal deposits in Colombia, where the gems occur in veins rich in carbonate, quartz, and pyrite, often contain inclusions of carbonate minerals. The shape of the carrier mineral usually determines the shape of liquid inclusions. Therefore, they are often called "negative crystals". A large number of inclusions makes it possible for thorough geological studies, such as: verification of the conditions for the formation of ore deposits, analysis of fluids for the exploration of oil fields, getting the age of diamonds and the associated conditions of formation, hypotheses about geotectonic conditions of the earth in different epochs, getting information about the ancient biosphere, study of the ancient atmosphere For gemologists, inclusions provide the basis for the identification of a gemstone, and in some cases it is possible to determine its specific origin. For example, the inclusion of the parisite in the emerald is a diagnostic sign of Colombian origin, or long thin rutile silk, which can be seen in Sri Lankan sapphire Finally, inclusions in precious stones create visual works of natural art. Random geological processes on earth have created these inclusions in natural, unprocessed gemstones without any human intervention.