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Jewelry rarity - kridite
Continuing our notes about stones that are rarely found in cutting quality and therefore are valued among collectors-gemologists, we will tell you about Creed. Aqueous calcium and aluminum fluoride with several additional anions, which is most often found in the form of white concretions, consisting of a microgranular aggregate. But sometimes you can find small (usually from 0.5 to 2.0 cm) transparent crystals of orange color or almost colorless, but the rarest and most desirable for collectors are purple-violet (reminiscent of amethyst). Creedite is sometimes cut, and although outwardly it resembles a light amethyst or orange kyanite, for connoisseurs it is a real find. It is not easy to cut this stone, since its hardness corresponds to the hardness of fluorite, and the cleavage is perfect, so to speak, “torment for the cutter”. And it's not easy to find raw materials for cutting. In connection with all of the above, faceted stones are very rare, and beautifully colored and without visible inclusions are very expensive. Despite the fact that crystals of creedite are of little use for making jewelry, they will adorn any collection of faceted inserts.
В геммологической практике бывают весьма увлекательные случаи с диагностикой ювелирных вставок
Но помимо редкости цвета и высокой стоимости таких камней, многие розовые камни выделяются одной замечательной особенностью – они проявляют плеохроизм, то есть в зависимости от положения осмотра камня он может иметь дополнительные оттенки – оранжевый или пурпурный.
Currently, gemstones are produced by two fundamentally different technological methods - the High Pressure - High Temperature method (“HPHT”, High-pressure & High-temperature) and the Chemical Vapor Deposition (“CVD”, Chemical vapor deposition) method. The "HPHT" method is the most tested classical synthesis method, which can be used both carbon deposition on diamond from flux melts and catalytic reactions. In "CVD" synthesis, diamond growth occurs on a seed during carbon deposition mainly from a gaseous medium at relatively low temperatures and pressures.
Jewelry and precious stones are just such a category of goods, when buying which you need to pay attention to many criteria.
Sogdianite is a rather rare mineral and more often it can be found as a collection material (moreover, in systematic collections), and it is extremely rare in jewelry.