Natural rubies are very rare, so they are precious, but it is not too difficult to synthesize rubies, so industrial rubies are all synthetic. 1999, a red and blue conjoined corundum weighing 67.5 carats was found in Changle County, Shandong Province, China. It is called "Yuanyang Gem" and is a rare miracle in the world. 20 12 Many ruby mines were found in the riverbed of Caracas River in Mo Yuxian, Hotan, Xinjiang, with the largest of 32.7 carats.
Ruby refers to red corundum, which is a kind of corundum, and its main component is alumina (Al? o？ )。 Red comes from chromium (Cr), mainly Cr2O3, and its content is generally 0. 1~3%, and the highest is 4%. The blue color containing titanium is called sapphire (quoted from Fundamentals of Mineralogy).
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At present, there is no unified standard for the classification and evaluation of rubies, which is mainly measured and evaluated according to 1T and 4C: transparency, color, clarity, cut and carat weight.
1. refers to the degree to which the gemstone allows visible light to pass. In the naked eye identification of rubies, transparency is generally divided into five grades: transparent, sub-transparent, translucent, sub-translucent and opaque. Transparent rubies are the most beautiful and naturally the most expensive. And so on, the next one is sub-transparent, and the next one is sub-translucent. Like jadeite, "the water is one point higher, and the price is ten times higher", the price of ruby with excellent transparency is quite high, and the high-grade ruby is often several times higher than the low-grade ruby.
2. color. This refers to the color of precious stones. Ruby red requires pure hair color, no evil color, or other colors, full color. Among them, "Dove Blood Red" has the most collection value, which is a bright and strong color that can almost be called crimson, and can better show the beauty of ruby.
Its red color is not only pure, but also highly saturated, giving people the feeling of "burning flame". However, the production of pigeon blood ruby is extremely rare. Under pigeon blood red, bright red ruby is the best, followed by rose red and pink. It should be noted that the light source will have a great influence on the color of ruby, so there are clear requirements for the observation method of ruby color.
3. clarity. Ruby is a kind of gem with relatively many impurities, and most rubies have cracks, flaws and cracks. But it is precisely because of many impurities and high purity that rubies are more precious. The inclusion of ruby does not necessarily absolutely affect its quality and price, but mainly depends on the position of these defects in the gem and whether it affects the eye effect of the gem. On the contrary, inclusions can also be considered as the natural characteristics of rubies.
4. Stop working. Ruby cutting is very important. Only exquisite and ingenious cutting can present the most dazzling and charming light of the "king of gems" ruby to the world. The standard cutting method of ruby is different from that of diamond. The processor will not cut according to the geometric design in order to achieve the maximum brilliant light, but will emphasize the aesthetic feeling of restoring the ruby itself.
For rubies with thicker colors, the best cutting bar is lighter than the average level, so that more light can pass through the ruby; For shallow and deep incisions, it is beneficial to reflect the color. A well-cut ruby reflects light evenly on the whole surface, and the light interacts with each other, making it warm, rich and dynamic. China didn't know enough about precious stones in ancient times, and many regrets caused by ignorance of cutting processing no longer exist today.
5. Carat weight. Ruby, like diamond, has the same quality, and the higher the weight, the higher the price, especially the high-quality ruby above 1 carat. Anything over 3 carats is rare, let alone over 5 carats. The reason why large carats of rubies are scarce is that millions of years ago, during the formation of rubies deep in the center of the earth, Cr gave them bright red, but at the same time, it was Cr that caused the fine lines and cracks on the ruby crystal. Therefore, a very small amount of ruby crystals can grow to a large enough size and crystallize under such conditions.
References:
Baidu Encyclopedia-Ruby