What stones are called precious? Detailed answer

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What stones are called precious? Detailed answer

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What stones are called precious?

To be considered precious, a stone must have certain properties. It must be beautiful, hard enough and strong enough, it must be rare and valuable enough. Diamonds, rubies and emeralds have all these qualities to a sufficient extent and are the most real precious stones. Precious stones, with rare exceptions, are minerals.

Minerals are inorganic (not formed from living beings) compounds of chemical elements that occur in the earth. There are 4 precious stones of organic origin: pearls, amber, coral, agate. They are formed by animals and plants. The beauty of gemstones depends on color, brightness or unique optical phenomena.

Brightness refers to the luminosity of a stone, or its ability to reflect light. Optical phenomena refers to the rainbow effect caused by the ability to refract white light. For example, colors play in a diamond so that it seems to be full of fire. Gems can be found in all colors. Ruby is deep red, emerald is green. Each gemstone has its own hardness and rigidity.

Hardness is the resistance of a stone to scratches and sawing. Rigidity is the resistance to fracture. Gemstones were formed using the same processes as other minerals. But they were formed under more favorable conditions, which made it possible to obtain transparent, beautiful stones.

Author: Likum A.

Random interesting fact from the Great Encyclopedia:

What idiom in many European languages corresponds to the Russian expression White crow?

An analogue of the Russian expression "white crow" in many European languages is the idiom "black sheep". Although if we call a white crow just an exceptional member of society, then by calling a person a black sheep, Europeans also hint at the undesirability of finding such a member in society. In this sense, the idiom is close to another Russian expression - "black sheep".

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Red wine, white wine, iron 19.03.2010

Everyone knows the rule: red wine is required for meat dishes, and only white wine for fish dishes. The Japanese, who consume large quantities of fish and other seafood in large quantities, know that they also give an unpleasant aftertaste with red wine. Japanese chemists led by Takayuki Tamura decided to find out what is the reason.

Experienced tasters were asked to sample red and white wines with scallops (a kind of shellfish) and were asked to rate the presence of an unpleasant aftertaste on a scale from 0 (none) to 4 (strong). It turned out that the wines that give the strongest taste with seafood contain a lot of iron.

To test, chemists removed the iron from the wines that contained it and added iron salts to the varieties devoid of it. Indeed, they began to give an unpleasant aftertaste with the scallop. We tried to add or remove other metals - zinc, manganese and copper, but they did not affect in any way.

The experimenters came to the conclusion that iron reacts with unsaturated fatty acids, which are abundant in fish and seafood, and volatile compounds with an unpleasant taste and smell appear.

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