Among jewels, diamonds are known as the "king of gems" and are deeply loved by the world. However, when people first buy diamonds, they are lured and kidnapped because they don't know the midpoint. The simple and feasible methods to identify the authenticity of diamonds are: [pencil identification method] After the diamonds are wetted with water, they are scratched with a pencil, leaving no pencil marks on the surface of real diamonds. Transparent fake diamonds such as crystal, glass and tourmaline will leave traces. [Pen Identification] Dip a pencil in ink and draw a line on the diamond. The lines of a real diamond under a magnifying glass are made up of dots. [Characterization] The diamond is so hard that it is difficult to leave a notch on it with a blade. In addition, a slight scratch on the glass with diamonds will leave more obvious white marks. Fake diamonds do not have this phenomenon. [Drip identification method] Wipe the upper facet of the diamond clean, and dip the end of a toothpick with a drop of water on it. The water droplets on real diamonds will take the shape of medium-sized round water droplets. The water droplets on the fake diamonds will soon disperse. [Optical Identification] Real diamonds have the characteristics of single refraction, radiant light and dazzling brightness, but you can't see fingerprints when you wear them on your hands. Fake diamonds, such as crystals, have poor dispersion and low refractive index, and fingerprints can be seen through the crystals. Finally, according to the maximum thermal conductivity of diamond, it is detected by diamond thermal conductivity meter. If it is a natural product, the thermal conductivity meter can hum and light up a red light, which is the most accurate and simple way to identify diamonds. The above methods can only be used as a preliminary assessment, not as a final result. To make an accurate appraisal, it is best to go to an authoritative jewelry inspection department for final appraisal. Jade can be divided into nephrite and jadeite, also known as jadeite. From the chemical composition, nephrite is a silicate containing calcium, magnesium and iron, while jadeite is a silicate containing sodium and aluminum. Here are some common methods to identify true and false jade articles: (1) Water identification method Drop a drop of water on jade articles. If it is dewdrop-shaped, it is real jade. (2) If the touch method is real jade, it will feel cold and lubricated by hand. (3) When jade is observed in light, the true jade is clear in color and evenly distributed in green. (4) The tip of the tongue identifies that the real jade on the tip of the tongue has astringency and the fake jade does not. In addition, you can also observe with a magnifying glass, mainly to see if there are cracks, and the value of cracks is greatly reduced. There are six criteria to identify the quality of jade, namely "color, transparency, uniformity, shape, percussion and luster". (1) Jade is the best, and the value of red and purple jade is only 1/5 of jade. If jade contains red, purple, green and white, it is called "Fulu Xi Shou"; If it only contains red, green and white, it is "Fu Lushou". The dull and yellow ones are inferior. If it is monochrome jade, the color is better. (2) Transparent and crystal clear as glass, without dirty spots, chaff and astringency is the top grade. Translucent and opaque jade are called intermediate jade and ordinary jade respectively. Before and during the Qing Dynasty, jade with red, green and white colors was called jadeite. In modern times, jadeite refers to generally transparent jade. At present, jadeite is transparent and green. (3) The color of jade is uniform. Although it contains white and green, the color is uneven and its value is very low. (4) Special-shaped jade can be processed into different styles according to different aesthetic requirements, and there is no special standard. Generally speaking, the bigger the jade, the better. (5) Cracks and cuts are common when knocking on jade, which are generally not easy to observe. If you knock with a metal bar or throw jade gently on the table, you can tell whether there is a crack from the clarity of the sound. The louder, the better. (6) There are black spots and flaws in jade that are not easy to be found by naked eyes. As long as you take pictures with a magnifying glass of 10 times, you can have a panoramic view. The quality of jade can be divided into 10 grades, and each grade can be subdivided into three grades: upper, middle and lower. Among them, white jade has the lowest value regardless of color and transparency. Natural jadeite is characterized by slight light color, without light blue (commonly known as evil color). There is also a synthetic jade, which is made of jade powder, crystal and salt water, and looks like a dark "old pit jade". The identification method is very simple, because it is different from natural jade in proportion. It can be said by hand or with a balance, and the heaviest one is the real jade. At present, some exquisite fake jade is often mixed in the market. The general methods to identify fake jade are watching, listening and testing. (1) mainly depends on the transparency, internal structure and luster of the crystal. Real jade is transparent, oily and shiny, with natural patterns, and the internal fiber state is not easy to imitate. (2) Real jade sounds crisp, while fake jade sounds dull. (3) Measurement is mainly about hardness. With the glass plate (friction hardness of 5.5) as the standard, except jadeite and turquoise, stripes can generally be drawn on the glass plate, and jadeite itself is complete. Fake jade is generally soft and can't scrape the glass. Common fake jade is generally made of plastic and glass. They are all amorphous materials with low hardness and low density, and they are also the essential characteristics of materials. Plastic, for example, can be picked with a steel needle or floated gently in your hand. Glass is bubble-like under light or sunlight, and amorphous under polarizer (there is no periodic change of light and shade when rotating), and there are raw materials for making spiral stripes. Among many members of the jade family, pushing jade is the most precious. It is a natural ore with extremely high hardness and little output. Its colors are mainly green and red. Red is scarlet and green is emerald, hence the name jade. (1) Classification of jadeite ① Super grade: brilliant green (emerald), apple green, glass bottom (translucent, fine texture), uniform and bright, free from impurities and cracks. Commodity grade: green, oily green land, slightly transparent, translucent grandmother green veinlets and mottled green. ③ Ordinary grade: lotus root powder mill, bean green, light green, fine white and slightly transparent. Opaque jadeite is generally only used as jade ornaments. (2) Quality identification of jadeite ① Texture. Natural jadeite is transparent or translucent in texture, and its surface is bright and shiny. If you look closely, you can see the nearly round and slightly transparent "salt particles" and the fibrous substances around them. ② Hardness. Natural jadeite is jadeite, and its Mohs hardness is 7 degrees. It will be carved by a sharp knife without leaving any trace. The hardness of fake jade is low, so a sharp knife can draw it out. 3 Emerald. When natural jadeite is observed under strong light, emeralds with other mineral particles can be seen, which are called Cui Hua or emeralds. Fakes made of glass, plastic and porcelain have no such "emerald" characteristics. ④ Relative density (specific gravity). Natural jadeite has a hard and dense structure, no bubbles, high density, and clear sound when knocking; Fake products have loose structure or bubbles, low density and hoarse knocking sound. ⑤ color. The real product is rich and pure emerald color. Some fakes are made of white jade, serpentine, Australian jade, Han Guoyu, marble and even various stones. After decoloring, it is filled with high-hardness plastic slurry and colored, or soaked in green liquid to make "colorful jade". Observing under strong light, you can see green lines, which are messy and small; Some do not show lines, but they are not clear, with poor gloss and lighter weight than the real thing. Put the fake into the melted wax liquid, and the injected pigment will slowly separate out. In this way, the detected sample will not be destroyed, and the authenticity can also be identified. Observed by Celsi filter, the added emerald is purplish red under the mirror, and the natural genuine color remains unchanged. Some fake jadeites are artificially melted by glass, with loose structure, uniform and dark green color, some with bubbles, and hoarse when struck with hard instruments. (3) The choice of jadeite depends on the color. See if the color is pure, rich and uniform, and use a spotlight flashlight to check whether there are hidden variegated colors. Rich, pure and uniform color, less impurities. Emerald green has a higher price, followed by red and purple. Among the greens, Mabel Miao, which is tender and yellowish, is the best, followed by ruby green, river green and oil green, and the green is evenly distributed. ② Observe the transparency. Observing under strong light, the higher the transparency, the better. 3 Listen to the sound. The knock on the door is crisp and pleasant. ④ Observe emeralds and stone flowers. According to light observation, jadeite has the flash of other mineral particles (namely emerald), and there are often massive white flowers called stone flowers. Both of them get twice the result with half the effort. ⑤ Look at cracks and dark spots. Some cracks exist in the raw ore, and some are caused by processing, so the less the better; Black spots are everywhere in jadeite, so it is better to have fewer and smaller ones. ⑥ Look at the processing level. Smooth surface, good polishing and good shape are preferred. Platinum is a natural white precious metal. The annual output of platinum is only one twentieth of that of gold, and it takes five months to extract one ounce of platinum from 10 ton platinum ore. Domestic platinum jewelry usually contains 90% pure platinum and is marked with "Pt900". Platinum has a natural white luster and will not fade after long-term wear. The hardness of platinum makes it the best friend of diamonds. And white gold is gold with some alloys, which appears white. It only contains 75% gold at most. White gold cannot be marked with Pt mark, only gold and its purity can be marked according to its purity. For example, 18K platinum can only be stamped with "18K" and "G750". In the international precious metal market, the price of platinum far exceeds that of gold, which is the highest among all precious metals. In addition, some white jewelry may be made of silver or coated with white metal, which may show its original appearance after a long time. Although platinum is sometimes commonly known as platinum, it should be called "platinum" in a strict sense. Platinum in platinum refers to the chemical element platinum. Therefore, the purity, rarity, durability and natural white luster of platinum are incomparable to platinum. Therefore, in fact, some jewelry marked "platinum" on the market is not platinum jewelry, so it is very important to look at the imprint on jewelry when choosing. ■ Identification of Platinum (1) Visual inspection method: marking: each piece of jewelry must be engraved with chemical composition seals, such as (PT 900) and (pt 750), and all seals starting with "pt" are platinum jewelry colors: platinum is tin white, that is, white with gray, with bright luster (2) Instrument inspection: hardness test: platinum. But it won't be scratched by nails. Density measurement: Platinum is extremely dense and feels heavy in your hand. The density measured by hydrostatic pressure method should be 265,438+0.43 g/cm. Burn it: the melting point of platinum is as high as 1.773 degrees. Burn with alcohol lamp or electric stove, and the color will not change. Acidity test: Platinum is chemically stable and insoluble in ordinary acids. Draw it on the touchstone. Try to use hydrogen peroxide under the condition of unchanged wear marks: take a little platinum powder and put it in a hydrogen peroxide bottle, and hydrogen peroxide will immediately produce bubbles. After the reaction, platinum is intact and it can still be used. Because of its unique characteristics, platinum has always been considered as a precious metal. In recent years, the International Platinum Association has strongly advocated it, making it occupy an increasingly important position in wedding rings. Platinum was widely used in ancient Egypt 3000 years ago. Archaeologists once found that the coffin of an Egyptian priestess was decorated with hieroglyphics made of platinum, which remained perfect for a long time without losing its original luster, fully proving the durability and stability of platinum. Platinum didn't start to glow until the first diamond was dug up in Kimberly Mine in South Africa. This year, the Italian Platinum Association launched a series of new wedding rings, and put forward seven characteristics of platinum, indicating that platinum is the best choice to become a precious metal. 1. The alloy with the highest purity of platinum contains 95% pure platinum, and 18K gold is 75% gold. The purity of a platinum jewelry is higher than that of gold jewelry. The rarest thing is that the world produces 140 tons of platinum every year, while the annual output of gold is 3300 tons. Only skilled craftsmen can make it. The melting point of platinum is higher than that of gold, so the technical requirements for workers are more skilled. 4. The most stable platinum is the metal with the strongest acid resistance, alkali resistance and high temperature resistance, and will not fade or change color. Platinum rings generally do not deform. 5. Platinum with good gloss and ductility has natural white and luster, which will not affect the color of gemstones and make them glow "fire". Good ductility also makes them suitable for processing. 6. Do not cause allergic reaction to the wearer. 7. Valuable and excellent. ■ Common identification methods of platinum 1. Color Zephyr: Pure platinum is white with bright luster, while platinum is beige and silver is white. Can be distinguished from the surface color. 2. Hand balance method: the density of platinum reaches 265,438+0.45. Through the balance test of the same volume of materials, platinum has a heavy feeling, which is heavier than gold (19.36), k platinum and silver (10.45). 3. Melting method: The melting point of platinum reaches 1773oC, which is much higher than that of K platinum and silver. General welding guns can't melt platinum, so they can identify the authenticity. And that color of platinum doe not change after cool. 4, marking method: platinum jewelry has a standard imprint. Internationally expressed by PT or PT. For example, the purity of PT950 platinum is 950%. 5. Natural gas method: put jewelry on the twisted gas stove mouth for a few minutes. If the jewelry turns red and heats up to light the gas stove, it is platinum products. This is because platinum can be used as a catalyst to promote the oxidation and heat release of gas and air, and make platinum turn red, thus igniting the gas. 6. Spot measurement method: A Put mercury on platinum, platinum will not be polluted, and gold and silver will be polluted by combining with mercury. B. Put some powder in the hydrogen peroxide bottle with a file at the edge or middle depression of platinum jewelry. Platinum can be used as a catalyst to promote the decomposition of hydrogen peroxide and release oxygen to churn up and down. ■ Look at the mark. Platinum jewelry usually expresses the texture of jewelry by the ratio of platinum to thousands, which is also one of the basis of jewelry pricing. Common signs are as follows: foot platinum: the platinum content is not less than 990, and the sign is "foot platinum" or "Pt990". 950 Platinum: The platinum content is not less than 950, and it is marked with "Platinum 950" or "Pt950". 900 Platinum: The platinum content is not less than 900, and it is marked with "Platinum 900" or "Pt900". The hardness of pure platinum is small, so in order to increase the hardness, a certain proportion of precious metals such as palladium, rhodium and iridium must be added. Pt950 contains 5% palladium, rhodium and iridium, and its hardness is still relatively low, so it is generally used for plain platinum jewelry. Pt900 contains 10% palladium, rhodium and iridium, and its hardness is just suitable for inlaying ornaments. At present, most platinum ring holders are made of Pt900, but a few manufacturers use Pt950 to make ring holders. Because metals such as palladium, rhodium and iridium are rarer and more expensive than platinum, the price of Pt900 is correspondingly higher than that of Pt950. However, many consumers have formed a habit of understanding gold in the past: the higher the purity of gold, the more valuable it is, and it is applied to the relationship between the quality and price of platinum. So some merchants take advantage of this, deliberately marking the price of Pt950 higher than Pt900, misleading consumers to buy, so as to obtain income, which is bound to be suspected of fraud. Gold jewelry refers to jewelry made of gold as the main raw material. The chemical symbol of gold is Au, with a specific gravity of 17.4 and a Mohs hardness of 2.5. Gold ornaments can be divided into pure gold and k gold according to their gold content. The gold content of pure gold jewelry is above 99%, and the highest can reach 99.99%, so it is also called "99 gold", "all gold" and "red gold". K-gold jewelry is made by adding other metals (such as silver and copper) to its gold material, which is also called "opening gold" and "molding gold". Due to the amount of other metals added, K gold jewelry with different K numbers is formed. The size and gold content of K number are as follows: 24K, more than 99%; 22K，9 1.7%； 2 1K，87.5%； 18K，75%； 14K，58.5%； 12K，50%； 10K，4 1.66%； 9K, 37.5% 8K, 33.34% 6K, 25% Among the gold ornaments, pure gold ornaments are soft in texture, easy to bend, golden in color, pure and soft, heavy in hand and heavy in feeling. K gold jewelry is slightly hard and toothless, and its color is yellow with white. With the decrease of K number, the white gradually increases and the yellow gradually becomes lighter. K gold jewelry is not as heavy as pure gold jewelry. In addition, pure gold and K gold jewelry are stamped. The seal on gold jewelry can be represented by the word "gold" or the English letter "Kg". When indicating the gold content, the words "99" or "24K" indicate pure gold jewelry, and K gold jewelry indicates the corresponding K number according to the different gold content. For example, K gold jewelry marked "18K" has a gold content of 75%. In addition, there are seals on the jewelry, indicating the origin of different manufacturers. Real gold jewelry, with standard, complete and clear seal, is an important identification mark. There are many kinds of jewelry that are easily confused with gold jewelry, including gold-plated jewelry, gold-plated jewelry, copper jewelry, copper alloy jewelry and so on. Let's briefly explain its various types: gold-plated jewelry is a layer of gold plated on the surface of other metal jewelry by electroplating. The color is similar to that of real gold jewelry, and it is golden and bright, which is difficult to identify when it is new. However, gold-plated jewelry is light, hard and toothless, and it is easy to fade when used for a long time. Some gold-plated jewelry that is not plated well is either red or white or flowery. Colored gold jewelry refers to 24K or 22K gold foil wrapped on other metal surfaces. If the k value of gold foil is too low, its softness is poor. The appearance of gold-plated jewelry is similar to that of real gold jewelry, which is glittering, difficult to fade and difficult to distinguish between true and false. However, a careful observation of the dents, included angles, backs, etc. of jewelry will reveal that the gold foil is uneven and peeling. If there is a broken joint on the jewelry, we can see that the cross section of the metal material is yellow outside and white inside. In addition, gold-plated jewelry is lighter in hand, harder in texture than pure gold jewelry, toothless, not easy to bend, and gold foil is easy to peel off when worn for a long time. The color of copper jewelry is yellow with red, false, dull, soft and light. Copper alloy jewelry (copper-tin alloy) is light in color, hard and light in quality, and it will make the skin black if worn for a long time. Whether it is gold-plated jewelry, gold-plated jewelry, copper jewelry or sub-gold jewelry, there is generally no seal similar to gold jewelry. Or stamps are different from gold jewelry, for example, some jewelry is engraved with the English letter "GK", which means "gilded". Or the signature trace is vague and crooked. Consumers should judge the authenticity of gold jewelry by identifying whether there is a signature on the jewelry, whether the signature meets the above requirements and whether the signature is clear. There are many ways to identify gold ornaments, and China folks have summarized a set of simple methods. The formula is: look at the color, weigh, listen to the rhyme, fold hard, grind on the stone, compare the cards, point with acid and fix the color. The first four sentences rely on perception and feeling; The last four sentences need tools and reagents. Look at the color first. According to the different luster and color of gold, pure gold, k gold, real gold and fake gold can be roughly distinguished. That is, red and yellow are the best gold, and the purity is above 95%; The fineness of positive yellow is about 80%; Cyan accounts for about 70%; Yellow is light gray, and the fineness is about 50%. Therefore, there is a formula of "seven green, eight yellow, nine five red, yellow and white with gray and half gold". For jewelry that has been hidden for a long time, there is a saying that "copper turns green, silver turns black, and gold never changes color". Second, look at the density. The density of gold is 19.32 g/cm3, which is about twice as heavy as that of silver, lead and tin with the same volume. Available formula: the mass (gram) of a certain gold jewelry is equal to the density compared with the volume (cubic centimeter) of a certain gold jewelry. Calculate the density of the measured gold jewelry. If the density is about 19.32g/cm3, it is pure gold or relatively pure gold, otherwise it is impure gold or colored gold (this method is not destructive to jewelry). Thirdly, the hardness of gold has the characteristics of ductility and low hardness, and it can be pressed into thin slices with a thickness of 12.7 microns. When the color is dark, you can scratch it with a pin or nail to leave traces. More than 97% of colored gold jewelry is folded two or three times, and wrinkles appear at the bend, also known as fish scales; Gold ornaments with a fineness of about 95% feel hard when bending, and the scales are not obvious; About 90% of gold ornaments are hard when bending, and there are no fish scales; Gold jewelry with many impurities will break after two or three bends; If it is made of gold, it will break when bent, and there are obvious sand grains on the cross section. When using this method, the width and thickness of jewelry should be considered. Thick and wide jewelry is harder, while thin and narrow jewelry is softer. Fourth, listen to the rhyme and look at the gold jewelry with great elasticity and good color. When it is knocked or thrown on the hard ground, it will make a dull and low sound of "poof, poof", which has no rhythm and elasticity. K gold has rhyme, sound and elasticity. The greater the elasticity, the sharper the rhyme and the worse the color. V. Identifying the color with touchstone The color of gold jewelry is determined by grinding the gold card (the gold medal with confirmed color) and the measured jewelry on the touchstone. The method should be carried out under natural light and fluorescent lamps, not under direct sunlight and incandescent lamps. Six, use the acid spot on the touchstone to grind out the identified jewelry and the correct brand of gold rail, and use a glass rod to test nitric acid on the gold rail. Because the chemical property of gold element is stable and does not react with acid, its color remains unchanged. If it is not gold or impure gold, the path of gold disappears or changes. The law of change is "three fast and three slow", that is, the low color disappears quickly and the high color disappears slowly; Mixed gold disappears quickly, while clear gold disappears slowly; Large mixed gold disappears quickly, while small mixed gold disappears slowly. According to the disappearance of the golden path, the color of gold ornaments can be determined by comparing cards. References:

. Com/news/2003-01-02/893854.html The identification of gold ornaments in ancient China was a simple method of five senses identification. At first glance, the luster of gold is much brighter than that of copper, iron and tin. From the color, you can roughly distinguish the fineness. Remember this sentence: seven points green, eight points yellow and ninety-five percent red. Hand-held: Gold has a high density, so it will be settled if you hold it in your hand. This is a rough density method. Listen: the gold ornaments fell to the ground, making a dull sound, without a crisp feeling. Because of its high density and toughness, the frequency after vibration is lower than that of other metals. There are also methods such as biting teeth and breaking hands, depending on the situation. At present, most general technical supervision and inspection institutions adopt X-ray method. There are other methods, which require certain equipment, but most people don't. Not much to say!