What are the precious stones?
What are the precious stones?
The legislation of the Russian Federation defines as preciousstones the following minerals: diamonds, emeralds, sapphires, rubies and alexandrites. Also included in the list are pearls (rough and polished) and amber. All other stones used in jewelry are considered semi-precious and ornamental.
Instructions
1
The state regulates the extraction, storage,transportation and carrying out any commercial transactions related to precious stones, issues licenses for the development of deposits, has exclusive rights to export diamonds and replenish funds through the purchase of particularly valuable minerals and metals. In addition, all illegally mined gems are state property.
2
In a wider, everyday sense, preciousstones are minerals that correspond to the aesthetic and technical requirements of jewelers. The most important factor in determining the value of a stone is its uniqueness. The rarer the mineral is found in nature, the more expensive the jewelry will be. Take into account the size of the nugget: large stones and crystals have a great chance to get into a private collection.
3
That the mineral could be called precious orsemiprecious stone, it should be beautiful. Jewelers assess the color and transparency of the stone, shine, the presence of inclusions that create an invoice or pattern. - The more transparent the stone, the more expensive. Topaz and tourmaline are much appreciated, than, for example, jade, having the status of ornamental. - The gleam of precious stones can be glass, diamond, pearly, or absent altogether. Of course, the creators of jewelry are more interested in shiny stones. - Refraction of light, that is, dispersion, creates the illusion of glow, therefore such minerals are in great demand. The highest dispersion index for diamonds.
4
Specialists in precious stones also drawattention to the various optical effects inherent in the very mineral or impurities contained in it. To them rank: - asterism - rays divergent inside the stone, resembling a star; - cat, falcon or tiger eye - characteristic fibers that cause associations with the eyeball; - opalescence and iris - color sparks visible due to the refraction of light in the stone. This phenomenon is noticeable in opals, moonstone, aventurine.
5
No matter how beautiful the stone was in appearance, withoutcutting and polishing it can not be used to create ornaments. Therefore, the performance characteristics of the mineral are extremely important: hardness, viscosity and chemical stability. Of course, pay attention to defects, cracks, pores and voids, which are a disadvantage, unless they form a beautiful pattern inside. In order to cut a stone on a plane, it must also be distinguished by a good cleavage, that is, it is neatly split in the given direction.
