Identifying gold requires some experience. Gold with different fineness has different colors and luster. After long-term practice and analysis, people have also summed up some simple basic identification methods. 1. Weight: The density of gold is higher than that of common metals such as copper and silver. The weight of gold in the same volume is 2.2 times that of copper and 1.8 times that of silver. So you can weigh it by hand first, and then judge the authenticity according to the size. Gold feels heavy by hand, which is called "falling gold hand", and vice versa. 2. Use acid spots: polish the gold thread track of the identified jewelry and the correct brand on the touchstone respectively, and try nitric acid on the gold thread track 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. Third, the color identification method: "Seven greens, eight yellows, nine reds, and four sixes are not gold", this formula is one of the methods to identify the fineness of gold. 1 .7 cyan means that 70% (including 70% gold) of gold is blue and yellow. 2. Eight yellows means that 80% (including 80% gold) of gold is yellow. 3. Jiutiaohong means that 90% and more than 95% of gold is deep red yellow, and 90-95% of gold is light red yellow. 4. Four or six does not show gold, which means that the color of gold is less than 60% (including 60%), and the color it presents is no longer the color of gold. The color of gold below 60% is yellowish and white, and the color of gold below 40% is completely white. Fourth, listen to the rhyme: throw the gold in a hard place, and the gold with high color will make a "plop" sound, which is dull and rhyming. After low-quality gold is thrown to the ground, its sound is slightly sharp and slightly high, slightly short rhyme. The bronze ornaments will make a "Dangdang" sound after being thrown to the ground, which is high and sharp, long and rhythmic, and will rebound after being thrown to the ground. V. Identification of color by touchstone: The color of gold jewelry is determined by grinding the gold pair (the gold medal whose color has been determined) 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. Sixth, fire identification: As the saying goes: "Real gold is not afraid of fire." Gold will not melt or change color at a high temperature of several thousand degrees. According to this, it can be burned on the fire, that is, it can distinguish between true and false. Seven, soft and hard: high-quality gold is soft; The fineness is second, and the hardness increases; The physical folding of copper bars is laborious and elastic. High-quality gold is scratched with a pin (nails and teeth can be bitten), with little strength but obvious traces; If brass jewelry is scratched with a pin, the trace is blurred and the nail is scratched without leaving a trace.