1, look at the color:

The best real gold is red and yellow. The true gold content is above 95%, the true gold content is about 80%, the blue gold content is about 70%, and the yellow and gray gold content is about 50%. After a long time, copper will turn green, silver will turn black and gold will not change color.

2. Folding hardness: Gold has the characteristics of ductility and low hardness, and can be pressed into thin sheets with a thickness of 12.7 microns. When the gold content is high, you can leave traces by scraping with pins and nails.

(1), more than 97% of gold jewelry, after bending for two or three times, wrinkles appear at the bend;

(2) Gold ornaments with a gold content of more than 95% feel hard when bending, and the wrinkles are not obvious;

(3) Gold jewelry with more than 90% gold content is hard and wrinkle-free when bending;

(4) Gold jewelry with more impurities will break after two or three bends;

(5) Made of gold, bent and broken, with obvious sandy section.

3. Listen to rhyme to see elasticity:

(1), when high-quality gold jewelry is knocked or thrown to the hard ground, it makes a dull and low sound of "poop-poop, poop-poop", which has no rhyme and elasticity;

(2) K gold has rhyme, sound and elasticity. The greater the elasticity, the sharper and longer the rhyme, and the lower the gold content.

4. Look at the density: the mass (gram) of a gold ornament is equal to the density compared with the volume (cubic centimeter) of a gold ornament. The density of gold is about 19.32 g/cm3. If it is not within this range, it is impure gold (colored gold).

5. Identify colors by touchstone: compare them under fluorescent lamp and sunlight by contrast method;

6. Use acid spots: grind a gold thread on the gold jewelry, and then drop nitric acid on the gold thread with a glass rod. If it doesn't change color, it is real gold. If the gold trace disappears, its change is that the gold content is impure.