In gemology, gemstones are generally divided into precious gemstones and semi-precious stones. There are five main types of precious stones, namely diamonds, rubies, sapphires, emeralds and opals (only the cat's eye of gold emeralds can be called opal), while the rest of the stones, such as crystal, agate, and carnelian, are semi-precious stones.
There are many varieties of semi-precious stones, and the main semi-precious stones are:
Topaz
The mineral name of topaz is citrine, which is called Topaz. As consumers confuse the names of topaz with yellow jade and citrine, the English transliteration name "topa" is used commercially to label gem-quality topaz. Topaz has a high brightness, transparency and luster, and the processed gemstones are a good and cheap alternative to natural corundum and diamonds.
Topaz is a hard, bright gemstone with a range of soft colors due to impurities or color elements. The most common natural colors of topaz are yellow, tan, brownish orange and pinkish brown. Topaz is often optimized, for example, irradiation can turn a colorless topaz into a blue color, and even a milky green color resembles the color of a precious Paraiba tourmaline. Topaz is a transparent gemstone that usually contains inclusions, most likely a two-phase inclusion, or a three-phase inclusion containing a bubble liquid and small crystals. There may also be cracks, streaks and veil inclusions.
The crystals of topaz are usually large and have good abrasion resistance and are resistant to scratching of most substances. Topaz has a high density, like garnet, which is much heavier than a gem of the same size.
Do not wear topaz jewelry when exercising or doing heavy work to avoid irreparable damage caused by collision. Although the Mohs hardness of gemstones is relatively large, due to the brittleness of topaz, it may cause the topaz to crack along the cleavage direction when encountering bumps. Always pay attention when wearing it, especially when wearing topaz bracelets, and other If dangle earrings and stud earrings are not directly involved in the touch, don't worry about bumping.
Even natural yellow-brown topaz will gradually fade in the sun, so jewellery with topaz should be avoided to the sun exposure and heat.
Garnet
As a general term for a mineral family, its English Garnet, derived from the Latin Granatum, means "granular, like seeds." According to the English transliteration, a few people in China also call it [JiaNeiShi". In China's jewelry industry, the name of the garnet is "ZiYaWu". "YaWu" is derived from the Arabic Yakut (ruby), and because the garnet is often purple, it is called purple tooth.
Garnet has rich varieties and colors, from the common blood red magnesium aluminum garnet, deep red to black iron aluminum garnet, bright purple red iron magnesium aluminum garnet to rare and precious emerald green garnet . The price of garnet is usually also directly related to his color.
Garnet has a glass luster and its main counterfeit is red glass. Natural garnets usually have mineral inclusions. For example, the water-calcium garnet of the currants color contains black magnetite and forms small black spots on its surface. Garnet has a large density, which makes it heavier than a gem of the same size.
Garnet is a hard and wearable gemstone, but it has no cleavage and uneven fracture, and the texture is somewhat brittle. Avoid hitting corners when wearing cut-face garnets.
Feldspar
Feldspar is a very attractive gemstone. It has a large number of natural colors, large particles, high cost-effective, and beautiful optical effects, so that people never tire of its color. Feldspar generally has a bronze luster, opal halo or feldspar halo. These words are all used to describe the effect of feldspar placed under light. The surface of the gem has a shimmer effect. The light looks like it's just below the surface of the gemstone. Moonstone is known for its special optical effects, and the reflected light on the surface of the stone creates a blue or white bronze luster. Internal reflections or interference effects can also cause stuns, and the halo in the elongated stone is an example. Feldspar gemstones are divided into two main categories: common feldspar (including moonstone, common feldspar and amazonite) anorthose (including anemousite and alluvial feldspar)
Moonstone
Moonstone is a feldspar with a faint color. Moonstone is a lucky stone in the traditional sense. It can arouse people's passion and is often presented as a gift between lovers. The surface of the moonstone may show its strong blue bronze luster and be transparent. It may also be due to the translucent or creamy exterior light of the gemstone. The moonstone may have a magical cat's eye effect or starlight effect. Bronze luster is the result of light reflecting from the interbedded layers of alkaline feldspar and feldspar. The thinner alkaline feldspar layer produces blue, while the thicker feldspar layer produces white bronze luster.
In addition, moonstone has a range of other colors and different properties. Such as blue moonstone, it has a clear and transparent bronze-gloss surface, the stronger the blue bronze luster, the more beautiful the gem, the more attractive it is, but now it is difficult to find such high-quality raw materials, the price is also increasingly, there are glass imitations. Secondly, there is the iridescent moonstone, which has a cloud-like appearance inside the speckled silky shape, which is caused by the white feldspar layer and inclusions, usually found in the inlay of silver.
Amazonite
Amazonite is an attractive opaque gemstone, it has green and white bands, or has a single blue-green color. Even in a single color, the color distribution of gemstones is irregular. Amazonite may also be yellow, pink, red and grey. But blue-green is the most popular color. Amazonite usually has a glassy luster, but it may show bright flash. Amazonite is sensitive to pressure and slightly brittle.
Turquoise
Turquoise is derived from the French Pierreturqoise, which means "Turkish stone", but Turkey does not produce turquoise. The reason why it is named Turkey Stone is that the turquoise produced by Persia needs to be shipped to Europe via Turkey.
Turquoise is popular in Asia, and many ancient civilizations believe that turquoise has the ability to heal and cure some mental power. In the history of the Arab countries, turquoise is a lucky gem that protects against wearing evil and can cure many diseases. Native Americans, ancient Inca and Aztecs also worship this jewel, and in their unearthed relics, a large number of intact turquoise-inlaid ancient jewellery was found, including amulets.
The traditional color of turquoise is sky blue. Iran was once considered to be the world's best turquoise producing area, but its turquoise mine has been exhausted, so the real estate green Turquoise is rare and precious. At present, the world's finest turquoise is from the Sleeping Beauty Mine in Arizona, USA. The mine produces very pure dark blue turquoise.
Turquoise is a very valuable gem material, and there are a large number of counterfeit products on the market and optimized treatment methods to improve the appearance of turquoise. In addition to glass counterfeits and enamels from the Victorian era, borosilicate, fossil bones, limestone and dyed chalcedony are also commonly used to pretend to be turquoise gemstones and materials. In addition, the turquoise powder or the small turquoise block is bonded and baked with a liquid synthetic gum, and once solidified, colored and cut, it can be carved like a valuable azure natural turquoise. Heating such small pieces of turquoise can produce a very stimulating plastic taste.
Turquoise has a low density and is a soft polycrystalline gemstone with a shell-like fracture, so it must be carefully scratched or scored when worn.
Amethyst
Amethyst has always been the most popular crystalline quartz. A large number of jewellery have amethysts from the 19th to the 20th century. Amethyst produced in Russia has always been considered the best because the gems under artificial light are red. However, amethysts have different purple tones, from light purple (rose) to dark Siberian amethyst, which is the brightest magenta when processed into facets. The term Siberia is also used to describe any thick purple crystal, no matter where its origin is. A deep purple crystal with a uniform color distribution is much more expensive than a light crystal, of course, not on the basis of black.
Rose quartz
Rose quartz, also known as rose crystal, has a color ranging from light pink to deep pink. Most rose quartz inclusions are severe or contain a cloud-like or translucent appearance. Clear gem-quality rose quartz has limited production and are expensive, especially for deeper colors. Because of the serious inclusions, the rose quartz has various cracks inside, so be careful when wearing or storing.
Tiger eye stone
The tiger's eye is a gemstone with a cat's eye effect. It is mostly yellowish brown. The gemstone has a silky light pattern, which is a variant of petrified wood. The quartz fiber of the tiger eye stone is shorter than the petrified wood, and the direction is irregular, and it is arranged in any direction like the marking. It is usually brownish yellow, blue, reddish brown, etc. It is opaque, fine and tough, and has a fine fibrous structure. If it is ground into a curved surface from the vertical fiber direction, a parallel movement will appear on the curved surface. The eye is named tiger eye because of its shape and color like tiger eyes. Africa is the main producing area, is the national gem of South Africa. The eye-shaped strip of the tiger eye stone is caused by the intrusion of iron oxide. This gem has a wonderful optical effect. Quartz replaces the tightly arranged asbestos fibers, and the fibrous structure makes the gemstones appear shimmering on the gemstone surface.