Rock crystal is a rare mineral, a kind of gemstone, quartz crystal, belonging to the quartz family in mineralogy. The main chemical component is silica, and the chemical formula is SiO2.
Forms colorless and transparent crystals when pure. When it contains trace elements such as Al, Fe, etc., it is pink, purple, yellow, brown, and the like. Different types of color centers are formed by irradiating trace elements to produce different colors such as purple, yellow, brown, pink, and the like.
The inclusion of inclusion minerals is called inclusion crystal, such as hair crystal, green ghost, red rabbit hair, etc., the inclusions are rutile, tourmaline, actinolite, mica, chlorite and so on.
Crystal refers to the colorless and transparent silica crystal, which is a valuable ore. Nowadays, it is included in the category of colored gemstones in parallel with iced chalcedony and tourmaline, and the yield is small. The ancient name is "water jade" and "water essence".
Quoting "Zi Zhi Tong Jian · Hou Jin Gao Zu Tian Fu two years": "The masterpiece of the Ziwei Palace, decorated with crystal." "Ancient and modern novels, Li Gongzi save the snake is the heart": "The utensils are glass, crystal, amber, agate For this, the song is ingenious, not in the human world." "Ai Qing poetry selection": "Condensed flower shape, love the quality of crystal."
Yu Jiejie's moonlight
Qing Hongsheng's "Changsheng Hall·Stealing Songs": "The chilly squats are high, and the curtains are scented by the wind." Qing Chen Weizhen's "Buddhist Man's Title Qingxi Relics Album" words: "I still remember hide and seek, crystal garden cool."
Rock Crystal is a quartz (Quartz) crystal mineral whose main chemical composition is silica and its chemical formula is SiO2. Western countries believe that as long as the crystal is transparent, the word crystal contains colorless and transparent glass (K9, ordinary glass blue), and also contains natural crystal ore. China's ancient crystal name is more than ten kinds of water, such as water, water, water, jade, etc. Therefore, in order to facilitate the distinction, the international crystal is usually referred to as (Rock crystal).
A well-developed single crystal is a hexagonal pyramid, so it is usually a block or granular aggregate, generally colorless, gray, milky white, and contains other mineral elements such as purple, red, smoke, tea, and the like.
When the crystal of silica is perfect, it is crystal; the crystal is not perfect is quartz: silica gel is dehydrated and is agate; silica hydrogel is solidified and becomes opal; when silica crystal grains are less than a few microns, it is composed. Chalcedony, vermiculite, secondary quartzite.
Chemical composition: Silica, chemical composition containing Si - 46.7%, O - 53.3%. Multiple colors appear due to the presence of different trace elements or color centers.
Mineral composition: goethite, hematite, rutile, magnetite, tourmaline, garnet, mica, chlorite, etc. form inclusion crystals, such as hair crystal, titanium crystal, green ghost, etc. An inclusion containing a hair-like needle-like mineral that is visible to the naked eye is formed. Manganese and iron are called amethyst; iron-containing (; golden or lemon) is called citrine; manganese and titanium are rose, called rose quartz, which is pink crystal; smoke is called smoke crystal; brown is It is called sapphire crystal; black transparent is called sapphire crystal.
Crystal habit: Crystallized crystals are trigonal, often hexagonal columnar crystals, cylindrical cross-grain development, the column is a pointed or two-pointed tip, a number of long cylinders are connected together, known as crystal clusters, beautiful Spectacular, the shape can be described in a variety of ways. In addition to the common long column shape, there are also sword-like shapes, some if they are plate-shaped, some are like short columns, and some are like double cones.
Some are as small as fingers, some are as big as boulder; some are less than half, and some weigh more than 300 kilograms. Chairman Mao Zedong’s crystal enamel finally selected high-quality white crystal from Donghai County 105 Mine. At present, the largest piece of crystal is also from Donghai County, Lianyungang.
Color: colorless, light to deep purple, light yellow, medium to dark yellow, light to dark brown, brown, green to yellow green, light to medium pink.
Amethyst: light to deep purple.
Citrine: light yellow, medium to dark yellow.
Blue crystal: light blue, dark blue. Almost all blue crystals are synthetic.
Smoke crystal: light to dark brown, brown. Since Al3+ in the composition replaces Si4+, [AlO4]4-color is generated after irradiation.
Green crystal: green to yellow green. The color formation is related to Fe2+, and there is almost no naturally occurring green crystal on the market, which is usually an intermediate product formed by amethyst in the process of heating into citrine.
Hibiscus stone: light to medium pink, lighter in color. Usually it is pink because it contains a trace amount of titanium (Ti). It can have a transmission star effect.
Hair crystal: colorless, light yellow, light brown, etc., may be due to rutile, often golden, brown and other colors, including tourmaline often grayish black; containing erectite and grayish green.
Gloss: Glass luster. The break is grease luster. Gloss, an optical property of the surface of a gemstone that reflects light. Observe the luster of the crystal, you can hold it with your hand, and see the surface reflection by the light that the light or window throws in. The brightness of the transparent crystal is related to the glossiness.
Transparency: Crystal transparency is related to the quality and quantity of light passing through it. When the light is transparent through crystal fragments or sheets with a thickness of 1 cm or more, the reflected image can be clearly seen. If the base image is not clear enough, only the outline is visible, which is translucent.
Refractive index (RI): 1.544-1.553, hardly exceeding this range. (The refractive index is the ratio of the incident angle sine to the refracting angle sine when the light penetrates into the gemstone crystal from the air and produces a refraction phenomenon.)
Bifold rate (DR): 0.009 (maximum), this value is very stable.
Dispersion value: 0.013. Dispersion means that the refractive index of a gemstone varies with the illumination light. For example, a diamond refracts red light to 2.405; green light to 2.427; and violet light to 2.449.
Light: One-axis crystal is positive. The one-axis crystal interferogram seen under orthogonal polarized light is unique, and its black cross arm does not reach the center, forming a hollow pattern, commonly known as a bull's eye interferogram. The center portion is usually pale green or pale pink.
Polychromism: Colorless crystals are not polychromatic. Colored crystals have weak to strong pleochroism. They are expressed in different shades of body color.
Cleavage: No cleavage. The so-called cleavage refers to the property of cracking regularly to form a smooth plane in a certain direction when the mineral is struck. According to the degree of cleavage, it can be divided into five categories: extremely complete cleavage, complete cleavage, medium cleavage, incomplete cleavage and no cleavage, and crystal belongs to no cleavage.
Fracture: shell-shaped. The fracture is also called a breach. It refers to the irregular cracking of the mineral after being hit, and the cracked surface is called the fracture. According to the shape of the fracture, it can be divided into a shell shape and a zigzag shape.
Hardness: Mohs hardness of 7, which is Mohs hardness, which is equivalent to hard steel. In 1824, an Austrian mineralogist named Frisch Moss extracted 10 varieties from many minerals and measured their relative hardness through scientific experiments, resulting in a crystal hardness of Mohs 7. Although the US National Bureau of Standards later used and promoted the more scientific Nopp hardness tester, jewelers in many countries around the world are still accustomed to the Mohs hardness table.
Density (specific gravity SG): 2.66 (0.03, 0.02) g/cm3. This means that the weight of a certain volume of crystal is 2.56-2.66 times the weight of the same volume of water. The density of the block variant crystal may be slightly higher.
Piezoelectricity: When a crystal crystal is subjected to pressure, it generates a charge; on the contrary, when subjected to a voltage, the crystal generates a high-frequency vibration. Crystal has the property of transferring pressure and charge to each other, called piezoelectricity.
Streak color: colorless. The color of mineral powder is called streaks. It can eliminate false colors, weaken the color, and retain the self-color, which is one of the more reliable identification features than the color of minerals.
Melting point: The melting point of the crystal is 1713°C. Its heat-shattering properties were discovered during the experiment. Put the crystal in the flame of the burner, unless it is well protected and slowly cooled, the crystal will be easily broken. This temperament, the ancients have been through.
1.Piezoelectric effect: Under the action of mechanical force (pressure or tension), the two ends of the crystal single crystal will generate electric charges, and their electric quantities are equal but opposite signs. In the industry, colorless, defect-free, non-double crystal crystals are often used as piezoelectric quartz plates.
2.Thermal conductivity: better than glass, but compared with most minerals, and has directionality.
3.hot melt: crystal is difficult to melt, melting when the temperature reaches about 1715 ° C, can reduce the melting point when there is inclusion.
4. boiling point: 2477°C
5. chemical stability: very good, only dissolved in hydrofluoric acid at room temperature, not dissolved in other types of acids, alkalis. It can be dissolved in sodium carbonate solution under high temperature and high pressure conditions.
6. Solubility: Crystal is insoluble in water at normal temperature and pressure.
Mostly under the ground, in the cave, there needs to be a rich source of groundwater. The groundwater contains more saturated silica. At this time, the pressure is about twice to three times that of atmospheric pressure, and the temperature is 550. Between -600°C, and given the appropriate time, the crystal will crystallize into a hexagonal column crystal according to the natural law of the "hexagonal system".
Generally, in an ideal environment for artificial control, that is, physical and chemical conditions satisfying the above conditions, the growth rate of the crystal is about 0.8 mm (mm) per day. This is also the standard production speed of many artificial crystal laboratories and factories.
The crystals thus cultivated are so-called "synthetic quartz", which are usually cut into chips for use in electronics, computers, and communications industries; some are called "cultivated quartz" (cultured). Quatrtz), although using different nouns, actually speaks the same thing. Generally, artificial crystals for industrial use have a thickness of about three centimeters, that is, 30 mm, which takes about 40 days to grow; if it is to be used as a crystal ball for grinding in a jewelry industry of ten centimeters (100 mm) or more, it is usually about It takes 120 to 180 days to get enough. However, this is the most ideal environment under artificial control.
It is possible to have this speed. In nature, the situation is not so optimistic, because the conditions of raw materials, water quality, temperature, pressure, etc. are constantly changing. It's hard to get the ideal situation, usually it takes tens of thousands of times, or millions of times, to achieve the same growth. This is also why the "geological age" movement is based on "millions of years" and is also a precious part of "natural crystal".
When normal crystals are grown, growth lines parallel to the ridgeline of the cylindrical tip can be found. Because of the narrow growth space in the underground and caves, especially in the event of an earthquake, or when the earth's crust changes, it is even more likely to be squeezed by other ores, often resulting in different "crystal faces".
Also, when the crystal is still in liquid form, it is often coated with other ores and ash to crystallize, such as rutile (later becomes crystal), volcanic ash (later into phantom crystal) and many more. All of these are "part of nature", please don't consider it as "defects ".
Crystal formation conditions are more demanding than ordinary quartz. First, there needs to be sufficient and stable growth space; secondly, hydrothermal fluid rich in siliceous minerals, slightly alkaline and low salinity; third requires low-high temperature (160 0C -400 0C, medium A high pressure (2-3 atmospheres); a fourth need to have a certain growth time, these four conditions can be used to generate crystal. In nature, the development of joint fissures and faults is a good space for crystal growth.
Granite development or The metamorphism is strong and provides sufficient hydrothermal fluid. The hydrothermal fluid itself has good temperature and pressure. The time factor is more easily obtained, so the crystal output on the earth is more extensive.
Crystals are often produced in the form of crystal clusters and crystal cavities. Crystal caves are generally found in igneous rocks and basalts of thick lava flows formed by volcanic eruptions.
The gas or hot water contained in the volcanic eruption causes a large number of pores in the rock formation. When the fluid rich in siliceous minerals enters the pores of the thin lava, and the crystals are precipitated, the crystals are precipitated when the temperature and pressure conditions are suitable. mineral.
Crystal origin The endogenous deposits of crystals are pegmatite, hydrothermal and skarn; exogenous deposits are common in sand ore. Gem-quality crystals are mainly produced in crystal caves or pegmatite veins, and crystals are produced almost everywhere in the world. Such as Madagascar, Zambia, Brazil, Germany, Russia, Myanmar, Afghanistan and so on.
China's crystal deposits are also widely distributed, with more than 25 provinces and districts producing crystals.
The genetic types of crystal deposits in China are mainly divided into four types:
1. granite pegmatite crystal deposits, such as the Chastai crystal deposit in Urad Middle Banner, Inner Mongolia;
2. quartz vein crystal deposits, such as the most famous “Crystal Home” in China. "A crystal deposit in Donghai County, Jiangsu Province;
3. skarn-type crystal deposits, such as the Chaoyang Bay crystal deposit in Bahrain Right Banner, Inner Mongolia;
4. crystal sand deposits, which have high hardness and are not easily weathered, often forming residuals, slopes and alluvial deposits. Crystal sand mine.
Cutting, pressing, rough polishing, fine polishing, punching, engraving, sand blasting, viscose, quality inspection, packaging.
Faceted, flat, faceted and flat and hand-carved.
1. Cutting material: It is the shape and size required to saw the whole piece of material with a large saw blade at high speed.
2. Embryo: The size and shape of the finished product are made by the mold, and then the raw material is heated to 900 ° C or higher to melt, flow into the mold, and die-cast.
3. Rough polishing: It is the blank that pushes out the mold and directly grinds out the finished line with a diamond disc.
4. Fine polishing: After rough polishing, the finished product is polished to a crystal clear finish.
5, punching: before the crystal finished product is not completed, according to the size and position of the required punching, processing with drill bits, such as watch parts, pen holders, bottle holes and so on.
6, silk screen: crystal surface with different color materials for effect processing, the color layer is thicker, after the force can fall off.
7. Plating: Using similar plating methods, the crystal surface has different colors, the layer is thinner, and it can be scratched by friction. Scratches appear. Because the plating is often located at the bottom, other objects are often attached at the bottom of the plating. Such as the birth of the town of Wenxiao.
8. Engraving: strong three-dimensional sense, high technology, fine workmanship and high cost. Hand-carved graphics, machine-engraved text.
9. Sand blasting: The three-dimensional feeling is weak, relatively flat, no embossing, and the effect is processed after the machine engraves text and graphics. Low cost and fast production.
10, laser engraving: computer-aided laser equipment in the crystal object for three-dimensional pattern molding, artistic effect is good, you can arbitrarily express all kinds of patterns, graphics, to achieve realistic effects.
After introducing the scientific analysis and verification of crystal, let's take a look at the classification of crystals. The classification of crystals is varied and can be roughly divided into three categories:
Crystalline Varieties crystal
Usually we see a cluster of crystals formed by a number of hexagonal crystal columns (hexagonal crystals), which belong to Crystalline Varieties, such as white crystal, amethyst, citrine, powder crystal, crystal, tiger eye. Stones and the like are all such.
Crypto crystalline Varieties
The appearance of cryptocrystalline crystals is a block, not a hexagonal crystal cluster, but they are also hexagonal. However, we can't observe their hexagonal crystals with the naked eye, because the volume of crystals is extremely small, and it is necessary to use a microscope to see the hexagonal open crystal.
And this type of crystal is very smooth, because there is a "hydrated silica" between the crystals, and agate belongs to this category.
Special Varieties special class
These crystals and general crystals are very large, and it is difficult to classify them as crystals or cryptocrystals.
Therefore, they are classified as special types, such as Skeeton Crystal, which is crystallized, and Phantom Crystal, which is a landscape image in the crystal. Phantom crystals and so on are summarized as such.
Crystal evaluation standards are different from high-end gems. Most high-end gemstones put color in the first place of evaluation, while for crystal, color and clarity (called crystal in the crystal industry) are almost equally important factors:
For any gem, color is very important, and crystal is no exception. If the crystal crystal is colored, such as pink crystal, citrine, amethyst, etc., the highest standard of color evaluation is bright and moving, without gray, black, brown and other colors. Such as pink crystal, the color is better than pink; amethyst, the color is required to be fresh purple, pure and not black; citrine, the color is not green, lemon color, preferably golden orange.
For hair crystals, the color of the crystal is also important. The same hair of the blonde crystal, the crystal is completely colorless (white crystal) and the crystal is slightly brown, the visual perception of the naked eye is also different, so the price of the former will be higher than the latter.
Crystal and high-grade gemstones have very different clarity requirements. High-grade gemstones are rare and rare, so it is generally not too demanding for the purity of high-grade gemstones.
The output of crystal is really amazing, so people usually ask for the higher the clarity of the crystal, and try to avoid crystals with more obvious inclusions.
If there are legendary characters in the interior of the crystal, such as Buddha, constellation, zodiac, etc., the value may be higher than the crystal of the same color and clarity.
The country has not yet provided a specific standard for the classification of natural crystals. The variety of crystals is complex, and each variety has its own different criteria.
Natural crystals are formed under natural conditions and grow deep in the earth's crust, usually undergoing intense crustal movements such as volcanoes and earthquakes. Natural crystal is a mineral resource, very rare and precious, and belongs to one of the gemstones.
Synthetic crystal is also called a regenerative crystal is a single crystal, also known as synthetic crystal, piezoelectric crystal. Regenerated crystal is a hydrothermal crystallization method that mimics the growth process of natural crystals. The natural silicon ore and some chemicals are placed in an autoclave and gradually cultured over 1-3 months (for different crystals).
It has the same chemical composition, molecular structure, optical properties, mechanical and electrical properties as natural crystals, and in terms of birefringence and polarization, regenerated crystals are purer and more lustrous than natural crystals. After processing (cutting, grinding, throwing), the particles of various shapes are crystal clear, dazzling, wear-resistant and corrosion-resistant.
There are many people in the market who call smelting crystals as synthetic crystals. It is inaccurate. It is usually smelted with crystal scrap as raw material under high temperature and high pressure, instead of being crystallized.
It does not have the crystal characteristics of crystal, so it cannot The smelting crystal is mixed with the synthetic crystal; but the smelting crystal is resistant to high temperature, and the smelting crystal smelted with high-quality silica can be made into practical products such as crystal cups, baking trays, tea sets, etc.
In fact, the crystal enamel of Chairman Mao Zedong is the selection of a great man. The high-quality crystal of the East China Sea is smelted.
K9 glass crystal
Some people also call K9 glass synthetic crystal, which is even worse. Although K9 glass is made from silica as the main raw material, 3-4% of lead is added during the smelting process. Crystal glass; why do you want to add lead? Generally, the glass is blue or green, and it doesn't look like crystal. But after adding lead, the whiteness of the glass is very high. It looks very like crystal. Especially the 3~4% K9 glass is the most crystal-like, so it is called K9 glass. Crystal is more appropriate.
World Crystal King from Brazil
Material: single crystal
Specifications: height 260cm 153cm
(The crystal weighs 28.6 tons, pure monocrystalline silica, and the shape is hexagonal)
The world's largest and most flawless a faceted amethyst, size: 71.5mm × 58.5mm × 46.3mm, cut into a faceted large drop shape. It weighs 1030 carats and is produced in Sri Lanka. It is dark purple with pink tones and saturated colors. The cutting and polishing ratio standard, the interior is extremely pure. This gem is by far the world's largest and most perfect faceted amethyst, and is also a boutique in the world's rare crystal boutique.
Crystal jewelry is getting more and more popular. People in China, Japan, South Korea, the United States and other countries also have a soft spot for crystal balls.
They like to put them in their homes or offices. They think that crystal balls are spiritual, can keep peace and bring wealth. However, natural crystal is not as crystal clear as it looks, it also has flaws, we should pay attention when buying jewelry. In addition, we also need to master the evaluation basis and purchase method of crystal, which can help us choose the crystal of our choice among the crystal jewelry.
Common defects of crystal Hidden crack
In the transparent crystal, the hidden crack is a sparkling sheet, and sometimes there is a halo effect. These cracks are some invisible cracks generated inside the crystal during the growth process due to external force extrusion. The hidden cracks are common in the hibiscus, amethyst, white crystal ball and white crystal columns. Some of the cracks were later filled with material, forming a healing crack, which means that the original crack grew. The effect of this crack on the crystal is relatively small.
2. Cotton, cloud or slag-like inclusions, impurities in the transparent crystal inside the fog or the feeling inside the cotton-like, slag-like inclusions, the presence of these inclusions, affecting the overall beauty of the crystal. In addition, some crystals contain dark spots or other colored plaques, which are inconsistent with the crystal as a whole, and are regarded as crystal impurities. Crystals with such impurities are defective.
After the crystal is formed, due to external force or some artificial reason, the crystal will have large cracks or cracks. The cracks are large and small, and the influence on the crystal is also divided into small and small.
4. Growth defects
The surface of the crystal is pitted, some deep and some shallow. This is naturally formed during the growth of the crystal, not caused by human damage. The defect position originally contained other mineral crystals. Because the bonding force between the inclusion body and the crystal bonding part is not strong, when the surface is polished, the ore body falls off and leaves a vacancy. This defect is common in green ghosts, titanium crystals, and blonde crystals.
Damage refers to the damage caused by crystals due to processing or accidental falling, collision and other reasons. It can be a breach or a pit.
Crystal evaluation basis
The evaluation of crystals is mainly based on its color, transparency, size, clarity, special patterns and whether there are optical effects. The color is pure, the concentration is high, and the interior is flawless. The amethyst is the most expensive, followed by citrine, smoky quartz, colorless crystal and hibiscus. Crystals with special optical effects are more expensive.
1. Color, transparency
In general, amethyst and citrine are the higher value varieties in the crystal. The further grading of the two is based on the depth of the color, the darker color is A grade, and the slightly lighter is grade B. Generally, the price is deeper and the price is higher, but it is not dark. There are two colors, one is the color of the crystal itself, and the other is the color of the inner inclusion. The color of the crystal itself should be bright and pure, and the distribution should be even, not too deep or too shallow, such as Australian jade, blue chalcedony, amethyst, and citrine, the price is high.
The colorless crystal contains bright colors of inclusions, and its price is also high, such as titanium crystal, green ghost, red rabbit fur. Amethyst is generally top grade with a slight cloud, dark purple color and crystal clear.
According to the transparency index, the more transparent the crystal, the higher the price, and the finished crystal made of good transparent crystal is crystal clear and brilliant. Crystals with high transparency can enhance the color of the color, otherwise it will be dull. Optical crystals require full transparency, no twins, and no impurities.
Process crystals require transparency, less cracking, and less smashing. The smelting crystal requires transparency and can have more cracks. The value of the three is reduced in turn, and the smelting crystal can only be used as a raw material for melting crystal glass. In the process crystal, the larger the crystal, can be used to make crystal glasses and engraving high-end crafts, so the price is higher.
2. Special patterns and inclusions
If the jade texture can form beautiful patterns and patterns, the price will be high. For example, the red and white colors in the agate are regularly arranged to form a sinuous agate. When the uneven color in the jasper forms a landscape pattern, the material The value will increase. When the crystal inclusions form a beautiful pattern, such as ghost crystal, landscape crystal, or needle-shaped inclusions in a bundle, the value is higher than ordinary crystal. The more beautiful the pattern, the better the artistic conception.
The value of hair crystal depends on the color, rarity and size of the hair, and is generally high in color and block size. The value of water crystals depends mainly on the size and transparency of the water bladder and crystals. If the water bladder is large and has a certain shape, it can be processed into more precious crafts. In addition, the water in the water bladder has a certain scientific value, through which you can understand the composition and changes of water on the earth millions of years ago.
3. Block size
The value of the crystal is also related to the size of the block. The same color and clarity level, the bigger the block, the harder it is. Sometimes the quality level is lower, but the block is large enough, and the price may be higher than the high-level small crystal.
The colorless crystal is famous for its crystal beauty, clean and transparent. The measurement of colorless crystals mainly depends on its purity. The purer and more transparent, the better. The value of clean, flawless, and less impurities is high. If the colorless crystal is dirty, there is no use value.
The less impurities and cracks, the better. For crystal products with good texture, there should be no gas-liquid inclusions or granules composed of star-shaped, cloud-like and floc-like distribution. If there are cracks or spots, it is a defective product.
6. Processing technology
Crystal and its quartzite jade are medium and low-grade gemstones. Although they are not as noble as diamonds and red sapphires, they are also of high value if they are ingeniously crafted and processed finely. For example, the traditional Chinese agate "shrimp plate", "long plate", "water Man Jinshan" (water agate ornaments) are known as national jade.
The value of crystal varies greatly depending on the quality, size of the block, aesthetics and yield. When you meet a good natural crystal, you have to dare to start, but good crystals are generally wanted by everyone. Values and worthlessness depend on experience. Due to the exploitation and production of natural crystals, it is difficult to obtain crystals without flaws. It is very difficult to obtain pure jewelry with quality comparable to synthetic crystals. In addition, due to the nature of the crystal, the grade is also changed during the wearing process, for example, for some reason, a large crack may gradually occur.
Crystals can be divided into different gemstone varieties depending on the color and special optical effects.
(1) Colorless crystal: colorless and transparent, the composition is pure and transparent, and large crystals without inclusions and cracks are difficult to see. Generally used as engraving materials, the most famous is the production of crystal balls, mainly as a kind of furnishings. The world's largest and transparent flawless water wafer ball, 21 cm in diameter, is now housed in the Smithsonian Museum in Washington, USA.
(2) Amethyst: Generally, the color tone is lighter and the color distribution is uneven. Amethyst also includes cyan and magenta transparent crystals. It is the most expensive one in the crystal. It is the birthstone of February, and it often has obvious dichroism.
(3) Citrine: Yellow-orange-red, brown-yellow, mostly transparent columnar crystals due to trace amounts of Fe. Currently, yellow-brown crystals discolored by amethyst heat treatment are often seen on the market.
(4) smoky quartz, tea crystal and smoky quartz: smoke yellow is called smoky quartz, dark brown is called sapphire crystal, black is smoky quartz. Some people think that these crystals are mainly mixed with extremely fine particles and evenly distributed carbon elements. Some people think that these crystals are formed by tiny particles (such as a large amount of gas or free silicon atoms). Others believe that the crystal contains a trace of A1, A13 + ions instead of Si < + ions, caused by the generation of hole color center after the administration.
(5) Crystal: A crystal variety containing slender rutile like black hair, black or colored tourmaline, green hornblende, white asbestos, and actinic stone like silk. This type of inclusion makes the crystal very beautiful. This crystal does not require fine processing, but can be used as a decoration with a little honing.
(6) Water Cholesterol Crystal: The crystal contains an inclusion of a natural mineralization aqueous solution visible to the naked eye. Because it is very rare, it is called a rare treasure.
(7) Rose crystal: a blocky crystal containing Mn and Ti in pink. In most cases, the crystal form is not good. In some crystals, due to the microscopic acicular rutile, they are at an angle of 120° to each other. The direction is perpendicular to the C-axis distribution. After honing into an arc, there is a six-shot starlight, also known as "Starlight Rose Crystal."
(8) Quartz cat's eye: When the crystal contains a large number of parallel fibrous inclusions (such as asbestos fibers), the curved surface of the gemstone can show the cat's eye effect, which is called quartz cat's eye.
(9) Starlight Crystal: When the crystal contains two or more acicular acicular and fibrous inclusions, the surface of the curved surface of the stone can show the starlight effect, generally six-shot starlight or four-shot starlight.