It seems necessary for everyone to know something about jewelry and jade. Moreover, the vast majority of precious stones belong to non-metallic minerals, which belong to the centralized management products of building materials industry. Therefore, employees of building materials system should know more about this knowledge, and consumers should know more about what jade beads: short for pearls, are beautiful calcium carbonate beads formed in shellfish. Its formation process is as follows: when small insects, small grains of sand, small bubbles and other foreign substances enter the body of the pearl oyster, they produce * * *, so it secretes a part of substances that build the shell (namely calcium carbonate) and wraps the foreign substances layer by layer. Over time, it has formed a dazzling pearl treasure: the abbreviation of gem.
All rare mineral crystals with magnificent colors and high hardness are collectively referred to as Gem Jade: short for Jade.
All mineral aggregates (rocks) with bright colors, high hardness and strong scarcity are collectively called jade, but corals in jade are not minerals, but calcium deposits secreted by corals in the ocean, mostly dendritic. As can be seen from the above definition, the main difference between gem and jade is that gem is a mineral crystal, while jade is a mineral aggregate (rock).
Secondly, the hardness of gemstones is higher than that of jade. The hardness of gems is usually 7 ~ 10, and the hardness of diamonds in gems is 10, which is the highest among all substances.
The Mohs hardness of jade is usually 4 ~ 7. The hardness of pearls is low, only 3.5 ~ 4.5. It is a special non-mineral gem.
Generally speaking, gems are more precious than jade. Gemstones are mostly used to make jewelry, and jade is mostly used to carve works of art. However, this is not the case in practical application. Large pieces of low-grade gem minerals are also used as carving materials, and good jade (such as high green jade) is also used as jewelry. Whether a rock can be used as a gem or jade mainly depends on its color, hardness and rarity. Color determines decoration, if the color is not beautiful, the decoration effect is not good, the hardness determines durability, if the hardness is low, the durability is poor, and whether it is rare or not determines preciousness. If it is not rare, it is not precious.
There are more than 230 kinds of mineral rocks that can be used as gems and jade, and there are thirty or forty kinds commonly used, most of which are non-metallic minerals, and only a few such as malachite and black diamond (hematite) belong to metallic minerals.
The mineral (or rock) names of the main gems are as follows:
In addition to the listed gems, good quality minerals such as tanzanite (zoisite), andalusite, diopside, epidote, pyroxene and tremolite can also be used as gems, and coal crystals and Tian Huangshi can also be used as jade. With the development of science and technology, new gem minerals and rocks will continue to increase. Liang Fang said earlier that there are more than 230 kinds of minerals and rocks that can be used as gems today. The value of different kinds of precious stones varies greatly, and usually precious stones are higher than jade. Gems and jade can be roughly divided into three grades according to their preciousness, while pearls are classified as gems.
High-grade gems include diamonds, rubies, sapphires, cat's eyes, emeralds, high-green jadeites and so on. Among them, diamond is the most precious gem and has the reputation of "the king of gems". A good diamond, 1 carat is worth tens of thousands of dollars. Not long ago, a 2.23-carat red diamond was exhibited in Paris, with a price tag as high as $42 million. Emerald is the greenest gem and has the reputation of "the king of green". She and other high-grade gems are very expensive. The middle-grade gems include pearls, topaz (topaz), ruby (spinel) metamorphic rocks, opal, purple tooth black, tourmaline and so on. Low-grade gems include plumbite and amethyst.
High-grade jade usually refers to jadeite (jadeite) Good jadeite is only produced in Myanmar, which is relatively rare. Its name comes from the jade bird. The male is red and called "Fei", and the female is green and called "Cui". But jadeite (jadeite) is mostly jadeite. The mid-range jade includes dushan jade (Nanyang jade), Hetian jade (nephrite), red coral, lapis lazuli, turquoise, malachite and Australian jade. Low-grade jade includes hibiscus stone, agate, Henan jade, Xiuyu jade, Dongling stone, wood stone, plum blossom jade, soft crystal (fluorite) and so on.
There is no strict boundary between the above-mentioned high, medium and low-grade gems. As the saying goes, "gold is valuable, jade is priceless", and low-grade gems with excellent quality can be upgraded. For example, a good metamorphic rock can be upgraded from a medium gem to a high gem, and a good metamorphic rock can also be upgraded from a low gem to an intermediate gem when necessary. On the other hand, if the high-grade gemstone has "stone grain" or "dirty color", its value will also drop sharply and be downgraded to middle and low grade.
The value of the same kind of gemstone varies widely because of its quality, origin and processing technology, so a comprehensive evaluation is needed. Generally speaking, the color is bright and pure, without tower pattern and dirty color, and the transparency is high (but pearls, corals, turquoise, etc. Are opaque), the larger the grain, the better, and vice versa.
(Excerpt from: Jewelry Boutique Discussion Area)