Looking at the color, according to the different luster and color of gold, we can roughly distinguish pure gold, k gold, real gold and fake gold, that is, red and yellow gold is better, and the fineness is above 95%.
Second, the density can be calculated by the formula: the mass (gram) of a gold ornament is equal to the density (cubic centimeter) of a gold ornament, and the density of the tested gold ornament is calculated. If the density is about19.32g/cm3, it is pure gold or relatively pure gold, otherwise it is impure gold or colored gold (this method has no damage to jewelry).
Triple hardness, high quality gold jewelry with nails will leave traces. More than 97% colored gold ornaments will be folded at the bend after being bent two or three times. About 95% colored gold ornaments will feel hard when they are bent, about 90% colored gold ornaments will be hard when they are bent, and gold ornaments with many impurities will be broken when they are bent for two or three times.
Listen to the rhyme and see the elasticity.
Fifth, the touchstone identifies the color, that is, the gold pair and the measured jewelry are ground on the touchstone, and the colors are compared to determine the color of the gold jewelry.