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 GK "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.
First, look at the color.
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 is the best color of gold, and the fineness is above K95%. 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 density.
The density of gold is 19.32g/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 gold ornament is equal to the density (cubic centimeter ()) of a gold ornament. Find out the density of gold jewelry. If the density is around () () 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). () three. Bending hardness
Gold has the characteristics of ductility and low hardness, and can be pressed into 12.7 micron thick slices. When the color is high, 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 to see the elasticity.
When high-quality gold jewelry is knocked or thrown to the hard ground, it will make a dull and low sound of "poof-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 quality. K
Verb (abbreviation for verb) uses touchstone to identify colors.
The gold pair (the gold medal whose color has been determined) and the measured jewelry are ground on the touchstone, and the color of the gold jewelry is determined by color comparison. The method should be carried out under natural light and fluorescent lamps, not under direct sunlight and incandescent lamps. ()
Sixth, use acid points.
On the touchstone, grind the gold channel of the identified jewelry and the correct brand respectively, and test nitric acid on the gold channel with a glass rod. 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.