Gold jewelry refers to jewelry made from gold as the main raw material. The chemical symbol for gold is Au, with a specific gravity of 17.4 and a Mohs hardness of 2.5. Gold jewelry can be divided into pure gold and K gold from its gold content. The gold content of pure gold jewelry is above 99%, and the highest is 99.99%. Therefore, it is also known as “Jiujiujinâ€, “Full Gold†and “Red Goldâ€. K gold jewelry is a jewellery made of other metals (such as silver and copper metal) added to its gold material, also known as "open gold" and "color gold." Due to the amount of other metals added, the K number of K gold jewelry is formed. The size and gold content of the K number are as follows:
24K, 99% or more; 22K, 91.7%; 21K, 87.5%; 18K, 75%; 14K, 58.5%; 12K, 50%; 10K, 41.66%; 9K, 37.5% 8K, 33.34% 6K, 25%
Among the gold jewellery, the pure gold jewellery has a soft texture, the teeth are bitten and printed, and it is easy to bend. The color is golden, pure and soft, and the hand feels heavy and has a heavy feeling. The texture of K gold jewelry is slightly hard, the bite is not printed, the color is yellow with white, and the number of K decreases, the white color increases, and the yellow color becomes lighter. K gold jewelry is not as heavy as pure gold jewelry. In addition, both pure gold and K gold jewelry are marked with a seal. The seal on the gold jewellery is useful for "golden characters" and also for the texture of "Kg". When the gold content is indicated, the words "99" or "24K" indicate pure gold jewelry. The gold jewelry of K gold is different according to the gold content, and the corresponding K number is marked. For example, the K gold jewelry marked "18K" has a gold content of 75. %. In addition, there are marks on the jewellery that mark the origin of different manufacturers. True gold jewelry, standard, complete and clear, is an important identification mark.
There are many types of jewelry that are easily confused with gold jewelry, some are gold-plated jewelry, some are gold-plated jewelry, some are copper jewelry, and some are copper alloy jewelry. Here is a brief description of it:
Gold-plated jewellery is plated with gold on the surface of other metal jewellery. The color is similar to that of real gold jewellery. It is golden and bright, and it is difficult to identify when it is new. However, the gold-plated jewelry feels lighter, the texture is harder, the teeth are bitten and unprinted, and it is easy to fade after a long time. Some gold-plated jewellery that is not well-plated, the color is not red or white, or hair.
Color gold jewelry refers to 24K or 22K gold foil on other metal surfaces. For example, the K number of gold foil is too low, and its softness is poor. The appearance of gold-plated jewellery is similar to that of real gold jewellery. It is glittering and not easy to fade, making it difficult to argue. However, if you carefully observe the depressions, angles, and backs of the jewelry, you can find that the gold foil is uneven and has a phenomenon of lifting the edges. If there is a broken joint on the jewellery, the section of the metal material can be seen from the outside. In addition, the gold jewelry has a lighter feel, and the texture is harder than pure gold jewelry. The teeth are bitten and unprinted, which is not easy to bend. It is easy to peel off when wearing gold foil for a long time.
The color of the copper jewelry is yellow with red, fake, darker, softer texture and lighter weight. Copper alloy jewelry (copper-tin alloy), the color is white, the quality is hard and light, and the color is worn for a long time, which will make the skin black.
Whether it is gold-plated jewelry, gold-plated jewelry, or copper jewelry, gold jewelry, generally do not have a gold jewelry-like seal. Or the printed label is different from gold jewelry. If any jewelry is engraved with the English letter “GKâ€, it means “gold platingâ€. Or the printed signature is ambiguous and skewed. Consumers should judge the authenticity of gold jewelry by identifying whether there is a seal on the jewelry, whether the seal meets the above requirements, and whether the seal is clear.
There are many methods for the identification of gold jewellery. The Chinese folks have summed up a set of simple methods. The slogans are: look at color, weight, sound, rhyme, stone, stone, acid, and color. The first four sentences rely on eyesight and the feelings; the last four sentences require tools and reagents.
one. Look at the color
According to the different luster and color of gold, it can be roughly distinguished from pure gold, K gold, real gold and fake gold. That is, gold is preferably reddish yellow, the color is above 95%; the positive yellow color is about 80%; the blueish yellow color is about 70%; the yellowish slightly grayish color is about 50%. Therefore, there are mouths for "seven green, eight yellow, nine five red, yellow and white with gray to half gold." For the jewelry that has been in the first time, there is a saying that "the copper turns green, the silver turns black, and the gold never changes color."
two. Look at density
The density of gold is 19.32 g / cm 3 , which is about twice as much as the same volume of silver, lead and tin. Available formula: the quality of a certain gold jewelry (gram) is equal to the density of a certain gold jewelry (cubic centimeters). Find the density of the gold jewelry to be measured. The density is 19.32 g/cm3, which is pure gold or pure gold. Otherwise, it is non-pure gold or color difference gold (this method has no destructive effect on jewelry).
three. Fold hardness
Gold is characterized by ductility and low hardness and can be pressed into sheets having a thickness of 12.7 microns. When the color is high, scratching with a pin or nail can leave marks. More than 97% of the gold jewellery, after bending two or three times, wrinkles appear at the bend, also known as fish scales; 95% of the color of the gold jewelry, feels hard when bent, fish scales are not obvious; 90% of the color of gold Jewelry, hard when bent, no fish scales; gold jewelry with more impurities, bent two or three times to break; if it is made of raw gold, the bend is broken, the section has obvious sand-like shape. When using this method, the width and thickness of the jewellery should be considered. The thickness and width are harder, and the thinner and narrower are softer.
four. Listen to the rhyme, see the elasticity
When the high-quality gold jewellery is hit or hit hard, it gives a dull, low-pitched sound, and has no phonology and no elasticity. K gold has phonology, sound, elasticity, and elasticity. The sharper the longer, the worse the color.
Fives. Use the touchstone to identify the color
Use the gold pair card (the gold medal that has been determined to be the color) and the jewelry to be honed on the touchstone to determine the color of the gold jewelry by comparing the colors. This method should be carried out under natural light and fluorescent light, and not under direct sunlight and incandescent light.
six. Acid point
On the touchstone, the jewels of the identified jewellery and the counter are separately ground, and the glass nitrate is used to test the nitric acid on the ruthenium. Because the gold element is chemically stable and does not react with the acid, the color does not change. If it is not gold or non-pure gold, the Golden Road will disappear or change. The law of change is "three fast, three slow", that is, the low color disappears quickly, the high color disappears slowly; the mixed gold disappears quickly, the clear gold disappears slowly; the large mixed gold disappears quickly, and the small mixed gold disappears slowly. Depending on the disappearance of the Golden Road, the comparison of the cards will determine the quality of the gold jewelry.
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