Diamond
The word diamond comes from the Greek word "adamas" which means invincible. It is insoluble in acids and alkalis, and it is formed by the effect of very high pressure and temperature of magma, and also originates from kimberlites. Among the precious stones, it is the simplest chemical structure. It is carbon. This stone is the most precious and hardest mineral on earth. Its hardness is 10 on the Mohs scale. The value of a diamond depends largely on its weight. A maximum of 3-4 carats will be extracted from one ton of ore. A carat diamond can cost up to $10,000 depending on quality. About 20 countries, including Australia, the United African Union, Russia, Brazil, Congo, Namibia, Angola, and Tanzania, are among the countries rich in diamonds.
Emerald
Emeralds are called "smargados" and come from the ancient Greek word for green. The precious stone is a type of beryl (Be3Al2(SiO3)6) and has a green color due to certain compounds of chromium and vanadium oxide, and has a hardness of 7.5-8 on the Mohs scale. It is very rare for an emerald to be uncracked. Almost all emeralds are treated to enhance clarity. The value of emeralds lies in their deep green color, and more recently, artificial emeralds have been produced by synthetic hydrothermal multiplication of colorless beryl. Colombia is the largest producer of emeralds in the world. It alone supplies 50–95% of the world's emeralds. A rare trapiche emerald, famous for its hexagonal structure, is found in Colombia.
Ruby
Ruby comes from the Latin word / ruby / meaning red. This precious stone is composed of aluminum oxide ( Al2O3:Cr ), but is colored red, reddish-purple, and violet due to chromium. It is one of the hardest stones with a hardness of 9 on the Mohs scale. In terms of origin, it is formed in syenite, pegmatite, and high-grade metamorphic rocks and occurs in alluvial deposits. Large, quality rubies are sometimes more expensive than diamonds. In the world market today, a ruby with a weight of 0.5-1.0 carats is sold for 500-4000 US dollars, 300-3000 US dollars if the quality is a little low, and 85-250 US dollars for slightly darker colors. There are few deposits of rubies in the world and they are found in Burma, Thailand, Sri Lanka and Tanzania. The main ruby deposits are in northern Burma, where only about 1% of all rubies mined are qualified. Rubies are found in very small quantities. Also, the largest ruby in the world was found in Burma, and its weight was 400 carats.
Sapphire
The origin of the name sapphire is not clear, it came from the Latin version of the Greek word sapphirus, and a similar word is found in Persian and ancient Hebrew. Blue corundum has been called sapphire. This precious stone is a first class precious stone composed of aluminum oxide (Al2O3). It can be clear, bluish-purple to indigo-blue. It is one of the hardest gemstones with a hardness of 9 on the same hardness scale as ruby, and it is formed in syenite, pegmatite, and high-grade metamorphic rocks regardless of origin. Large sapphire deposits are located in Burma, Madagascar, Sri Lanka, China, Vietnam, Thailand, India and Australia.
Pearl
Although pearls belong to the category of precious stones, they are organic products. Pearls are formed from mollusks. When some foreign object enters into shells, the foreign object is covered with hard white tissue, this process is repeated and the white tissue enlarges to form a pearl. White pearls are composed of aragonite (calcium carbonate aggregate) and conchiolin (corneal substance). Depending on the place of origin, pearls are classified as saltwater and freshwater, and depending on how they are formed, they are divided into natural and artificial. Natural pearl mining has become very rare in recent years. Because in order to find a single real pearl, you have to open the shells of thousands of tiny mollusks and kill them. Therefore, people prefer to make pearls themselves. The process is almost the same as in nature. The only difference is that people themselves insert foreign bodies into the shells. One pearl is formed within 2-7 years. It cannot be polished. Pearls should be handled with care. It is said to be 150 years old when it is used the most. But a 200-year-old pearl turns black and becomes unrecognizable.
