Natural ruby has a strong "dichroism". The so-called dichroism means that there are two colors of red and orange red from different directions. If there is only one color, it may be red spinel, garnet or red glass.
Red spinel and natural ruby are very similar, and they are most easily confused, so be very careful. Natural sapphires are often uneven in color, and most of them have a flat growth line. Artificial sapphires are of the same color, and their growth lines are arc-shaped strips, and they are often breadcrumb-shaped or beaded bubbles in the body.
Natural sapphire also has obvious dichroism, one direction is blue, and the other direction is blue-green. Other gemstones are different in color from natural sapphires and can be distinguished.
In addition, the simplest method can be hardness measurement. Natural sapphires can carve traces on topaz, while other sapphires are difficult to carve traces on topaz. Therefore, when buying jewelry, if there is no instrument around, as long as there is a topaz, sometimes some problems can be solved. Some people say that a piece of green jade was taken by Dow filter. If it turns red, it can be said that this jade is dyed, and if it doesn't change color, it is its true color. This statement is mechanical and parrot-learned.
Dow filter is a kind of filter that only allows red light and orange light to pass through. The fuel used for jadeite dyeing usually contains chromium salt. It will emit red light when its concentration is high, and it will appear red under Dow filter. However, if the dyed color is not deep, the concentration of chromium salt is not high, and it is red under Dow filter, which is not easy to observe. In addition, natural green jadeite sometimes contains a small amount of substances that emit red light. When observing green jadeite with Dow color filter, it needs to be carefully analyzed, which will be indicative and cannot make a conclusive judgment.
So what's the difference between natural green and dyed green of jadeite? I know that jadeite is dyed, and natural jadeite has three colors: green, white and purple, because the particles that make up jadeite have three colors: green, white and purple. Therefore, when we look at the color of a natural jadeite, its color and crystal are inseparable, while the original crystal of dyed jadeite is colorless. The dye that enters jadeite through impregnation permeates along the intergranular cracks or some tiny cracks of the crystal, so there is an obvious boundary between color and crystal. In recent years, there is a kind of glass fiber cat's eye ring on the market, which is embedded in gold or silver rings, making people unable to tell the true from the false. The identification method is that when the torus is rotated, several light bands can appear at the arc top of the fake cat's eye at the same time, while there is only one real cat's eye. The fake cat's eye eyeliner is rigid, while the real cat's eye eyeliner is flexible. True cat's eyes are mostly brownish yellow or light green, while fake cat's eyes are varied in color, including red, blue and green.
Golden emeralds are second only to diamonds and red sapphires in hardness. Golden emeralds and various changeable stones and opals are not only very beautiful, but also very expensive, because they are extremely rare. Opal is the color-changing effect after Kapson cut emerald with developed vacuum inclusions. jade
2. Natural jade: agate, jasper, lingbi jade, hetian jade, xiuyan jade, Nanyang jade, jadeite, lantian jade, malachite, turquoise, Dongling jade, Junggar jade, luminous jade, malachite, cryolite, lapis lazuli, golden jade, ice flower jade, Shi Ying, etc. 4. Natural organic gems: amber, pearls and corals.
In 1999, the top five were: xiuyan jade, Nanyang jade, Kunshan jade, agate and turquoise.
1. diamond: diamond is a crystal mineral which is completely crystallized from single element carbon, and it is also the only gem composed of a single element. Diamonds are octahedral cleavage, that is, the four directions of the plane octahedral crystal face are generally stepped. The chemical properties of diamonds are very stable and are not easily soluble in acid and alkali. But in pure oxygen, it will decompose when heated to about 1770 degrees. When heated to 1700 degrees in vacuum, it will decompose into graphite. Diamonds are transparent, translucent and opaque. Gem-grade diamonds should be colorless and transparent, with no or few defects, and can also be yellowish or extremely light brown. The most precious color is natural pink, followed by blue and green.
2. Pearl: Small impurities in seawater or fresh water enter the mollusk, which stimulates the mantle to secrete a kind of pearl (mainly calcium carbonate), which wraps the small impurities layer by layer and gradually turns into small round beads. This is the pearl. The color of pearls is mainly white, pink and light yellow, with pearl luster, and its surface is faintly shining with iridescent pearls. White color, bright skin, round shape, hard particle size, the highest value.
3. Turquoise: Turquoise is a kind of self-colored gem, which is completely hydrated copper aluminum phosphate. The molecular formula is cual6 (po4) 4 (oh) 8 5h2o (basic aluminum copper phosphate pentahydrate). The transparency of turquoise is opaque, and the lower part of the sheet is translucent. The polished surface is greasy glass luster, and the fracture surface is greasy dark luster. The types of turquoise are Persian turquoise, American turquoise and Mexican turquoise, Egyptian turquoise and wire turquoise.
4. Lapis lazuli: Lapis lazuli is a mineral of sodalite family; The molecular formula of lapis lazuli is (Na, Ca)7-8(Al, Si) 12(O, S)24(SO4) and Al2cl2 (OH) 2 (OH) 2, in which sodium is often partially replaced by potassium and sulfur is partially replaced by sulfate, chlorine or selenium. The types of lapis lazuli are Persian lapis lazuli, Soviet lapis lazuli or Spanish lapis lazuli and Chilean lapis lazuli.
5. Opal: It belongs to opal in minerals, and its molecular formula is SiO2 nH2O (hydrate of silicon dioxide). Because the sio2 _ 2 beads in opal are arranged neatly like a grating, when white light shines on it, it diffracts and scatters into a chromatogram, so opal has dazzling changing colors, especially red. The types of opals include white opal, black opal, crystal opal, fire opal, colloidal opal or emerald opal, megalithic opal, gangue opal or matrix opal.
6. Olivine: Olivine is a kind of gem with its own color. The common colors are pure green, yellow-green to brown-green. Olivine is not colorless. The molecular formula is (Mg, Fe)2SiO4 (magnesium iron silicate). The types of olivine include olivine, topaz, forsterite, fayalite, "Twilight Emerald" and boehmite.
7. Feldspar: According to mineralogical classification, feldspar can be divided into two categories: potash feldspar and plagioclase. The molecular formulas are KAlSi3O8 (potassium aluminosilicate) and NaAlSi3O8 (sodium aluminosilicate). The types of feldspar are moonstone or cryolite, moonstone or sandstone, Labrador stone, Tianhe stone or Amazon stone.
8. Jade: jadeite (also called jadeite) and nephrite. Jadeite is a sodium aluminosilicate, and its molecular formula is NaAl(SiO3)2. Nephrite is a hydrous calcium magnesium silicate, and its molecular formula is: CAG5 (OH) 2 (Si4o11) 2.
9. Timekeeping: Timekeeping is a gem of other colors, and pure timekeeping is colorless and transparent. The molecular formula is silicon dioxide. The types of seasonality include crystal, halo or Ayabeni seasonality, rutile speckled or reticulated rutile seasonality, amethyst, topaz, smoky seasonality or smoky crystal, hibiscus stone, Dongling stone, purple Shi Ying seasonality, milk seasonality, sapphire or sapphire Shi Ying, tiger eye, eagle eye or eagle eye, quartz cat eye and starry sky or starry Shi Ying.
10. chalcedony: also known as aphanitic time. The molecular formula is silicon dioxide. The types of chalcedony are moonstone, chrysoprase, red agate, carnelian, bloodstone, emerald chalcedony, agate, onyx, jasper, dark green chalcedony and silicified wood.
1 1. Garnet: Its crystal shape and color are very similar to pomegranate seeds, hence the name. The general molecular formula of garnet is R3M2(SiO4)3(R and m are certain elements). The types of garnet include almandine, magnesium almandine, magnesium almandine, manganese almandine, andradite and calcium chromite.
12. Zircon: red, yellow, blue, purple, etc. The molecular formula is ZrSiO4 (zirconium silicate).
13. Spinel: yellow, green and colorless. The molecular formula is MgAl2O4. The types of spinel include red spinel, ruby spinel or ruby spinel, purple or garnet-like spinel, pink or rose spinel, orange spinel, blue spinel, sapphire spinel or sapphire spinel, calcite spinel, black spinel, ferrimagnesite spinel or ferrimagnesite spinel.
14. Topaz: Topaz is aluminum fluosilicate with orthogonal crystal system. The molecular formula is Al2(F, OH)2SiO4. The varieties of topaz are brownish yellow to yellowish brown, light blue to light blue, pink and colorless.
15. Tourmaline: an extremely complex boroaluminosilicate, which may contain one or more of the following components: magnesium, sodium, lithium, iron, potassium or other metals. These elements have different proportions and colors. The types of tourmalines are red, green, blue, yellow and orange, colorless or white, black, variegated gemstones, cat's eye tourmalines and stone-like tourmalines.
16. Golden emerald: It belongs to spinel minerals and aluminate minerals. The main component is alumina beryllium, which belongs to orthogonal crystal system. The molecular formula is BeAl2O4. The types of olivine are metamorphic rocks, opals, metamorphic cat's eye gems and other varieties.
17. beryl: beryl is colorless in its pure state; Different varieties have different colors because of the existence of trace metal oxides. In the presence of chromium oxide or vanadium oxide, it usually becomes emerald, while aquamarine is colored by ferrous oxide. It becomes cesium beryl because of magnesium, while gold beryl is colored because of iron oxide. The molecular formula is Be3Al2(SiO3)6. The types of beryl are emerald, aquamarine, maxixe beryl, gold beryl, cesium beryl, other transparent varieties, cat's eye beryl, starlight beryl and so on.
18. corundum: corundum is a very common mineral. Apart from starlight gems, only translucent to transparent varieties can be called gems. The molecular formula is al2o3, which contains red chromium oxide, blue titanium oxide and iron oxide, yellow iron oxide, orange chromium oxide and iron oxide, green iron oxide and titanium oxide, and purple chromium oxide, titanium oxide and iron oxide. The types of corundum include ruby, star ruby, sapphire, bright sapphire and starlight sapphire.
19. Amber is an organic substance. It is a kind of petrochemical rosin, which contains some ancient trees related to rosin. The molecular formula is C40H64O4. The types of amber are Haipo, Kengpo, Gepper, Zhongpo, Lipo, Turbid, Bubble and Bone.
20. Coral: It is another bio-gem material. It is a dendritic calcium skeleton of coral, which is formed by the proliferation of tiny marine animals.
2 1. Coal jade: Coal jade is a kind of lignite (mainly composed of carbon and containing hydrogen and oxygen). It is compacted by driftwood and sinks to the bottom of the sea, becoming buried fine silt and then becoming hard shale, which is called "coal jade rock". Coal jade is biogenic. Coal jade is amorphous, rough surface is dull, and polished surface has glass luster.
22. Tortoise shell: amorphous, oily to waxy, with hardness of 2.5.
23. Synthetic corundum refers to an artificial material whose physical, optical and chemical properties are basically the same as those of related natural corundum.
24. Synthetic gemstones refer to artificial gem with basically the same physical, optical and chemical properties as related natural gemstones. Synthetic gemstones include synthetic rutile, strontium titanate, yttrium aluminum garnet, gallium garnet, synthetic cubic zircon, synthetic sapphire, synthetic spinel, synthetic rutile, synthetic metamorphic rock, synthetic diamond, synthetic emerald, synthetic opal and synthetic chronometer.
25. Double stone: also known as composite stone, this is a kind of gem bonded by two different materials. The types of double-sided stones are classified according to the properties of the materials used for bonding. Amphoteric stones include garnet and glass amphoteric stones, emerald substitutes, opal substitutes, starlight sapphire substitutes, diamond substitutes, and various other composite stones similar to gems.