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Orpiment
Today we will talk about a mineral used to obtain bright yellow paints, the name of which itself speaks of its original use - orpiment. This mineral has a bright yellow color, and its very perfect cleavage largely determines the characteristic golden-silky sheen of the mineral. This mineral, in addition to its use as a mineral dye, is also known as the main ore mineral for arsenic. However, it has found application in the manufacture of jewelry inserts - not only beautiful collectible cabochons are made from it, but also triplets (compound stones). Its hardness and very perfect cleavage make this stone of little use in utilitarian jewelry. But triplet cabochons, where the stone is used as a central insert (in the girdle area) between the quartz pavilion and the crown, have a much higher wear resistance, and the bright color of the stone gives such a cabochon an attractive look. Although this stone contains arsenic in its composition, its combination with sulfur is quite chemically stable and safe for use in jewelry. However, there are also contraindications - such cabochons cannot be heated on fire to a temperature above 200-250ºС, since the mineral begins to decompose, and the resulting arsenic compounds are unsafe for health. Also, the color of the stone may fade if it is exposed to direct sunlight or ultraviolet for a long time, which is also associated with its physical and chemical transformation. Therefore, composite stones with orpiment are more resistant to sunlight, as they do not have direct contact with atmospheric oxygen.
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.