Hydrothermal synthesis method

Hydrothermal synthesis is the process of crystal growth under hydrothermal conditions occurs at high regimes and pressures. Therefore, this process leads in special thick-walled vessels - autoclaves, made of special high-strength corrosion and heat-resistant steel. The autoclave shown in the figure is not large, its working volume is about 250 ml, which allows one to grow in one growth cycle about 100 g of emerald crystals. Autoclaves for the hydrothermal growth of quartz crystals, for example, are much larger - up to 6 m3 and they allow growing up to half a ton of crystals per one growth cycle.
Autoclave Loading Scheme
The essence of the hydrothermal growth of emerald crystals using the "Russian Emerald" technology is as follows. At the bottom of the working cavity of the autoclave, charge (4) - crushed natural beryl of non-jewelery quality is filled. Above it is a diaphragm (5) - a steel circular plate with holes, dividing the working cavity of the autoclave into two zones: dissolution (under the diaphragm) and growth (above the diaphragm). In the growth zone, place a frame (6) with one or more seeds (7) - rectangular thin plates cut from the highest quality emerald crystals grown in previous cycles. Further to the inner cavity adds the necessary amount of water and mineralizer (a mixture of a certain composition that increases the solubility of beryl in a hydrothermal solution). As a mineralizer in the technology of Russian Emerald cultivation, salts are used that are present in real pegmatite processes, during which the formation of natural beryl crystals occurs.
Thus, either natural substances or completely analogous to natural substances are used as initial products in the technology of Russian Emerald cultivation. The charged autoclave is sealed in its upper part and placed in a special vertical oven in which the autoclave is heated to about 600 ° C, and the pressure in it is increased to 1500 atmospheres.
Moreover, the lower part of the autoclave (the dissolution zone) is heated to a higher temperature than the upper (growth zone). In the dissolution zone, the hydrothermal complex of the charge components (beryl) is saturated. Saturated solutions from the dissolution zone as a result of natural thermal convection enter the growth zone, where they cool and become supersaturated. The excess substance from the supersaturated solution is deposited on the seed plates - the crystal of the emerald grows. The total duration of one growth cycle is 1 month, during which one or several crystals of emerald grow up to a total weight of up to 100 g, with a total length of up to 19 cm and a thickness of up to 2.5 cm.
Let's analyze the difference between the realization of laboratory and natural hydrothermal processes. The crust begins to crystallize with the formation of, for example, granite. At the same time, start to separate the gaseous components from the melt, first of all water, in which the additions of mineralizers dissolve, which is able to dissolve substances that are insoluble under normal conditions. Such an aqueous gas solution is called hydrothermal. At the end of the magmatic crystallization, a cavity is formed in the thickness of the Earth's crust surrounded by strong walls, composed of crystalline rock, filled with a hydrothermal solution. "Extra" substance - crystals grow. Comparing the natural and laboratory hydrothermal processes, we see almost a complete analogy between them - in a natural and hermetic autoclave, not of iron, but of solid granite.

Grow process

As a basis we take natural stones brought to Russia directly from the place of extraction of emeralds (Brazil). All raw materials are thoroughly cleaned and combined with seeding
The billet is placed in an autoclave and sealed
Autoclaves are placed in a special storage, where under the influence of high temperature and pressure, under conditions as close as possible to natural, a hydrothermal crystal grows
A month later, the autoclaves are removed from storage and extracted raw materials
Ready crystals are supplied to the cutting factory
A quality control procedure is carried out, which allows us to give a lifetime guarantee for TAIRUS gemstones