To determine if a diamond is real, test it with a diamond testing device that also tests for electrical conductivity within a stone. You can also place the stone over printed text as diamonds refract too much light to allow clear text to be seen through the stone.
While most diamonds do not show lines, shapes and clear letters when placed over text, diamonds with shallow cuts may do so. To conduct a third test, breathe on the diamond to determine how quickly the fog your breath creates clears. Because diamonds are good conductors of heat, they are able to clear the fog quicker than other materials. An inconclusive test involves comparing the weight of your diamond to the recorded weights of real diamonds of the same size.
Moissanite is able to pass the breath test and the test involving the diamond tester. Moissanite is a diamond simulant crafted in laboratories out of silicon carbide. It cannot pass the electrical conductivity test, however, which is why a diamond tester that includes an electrical conductivity tester is necessary. In terms of appearance, moissanite gemstones have rainbow-like brilliance and yellow or grayish hues, while diamonds are typically clear ? although colored diamonds do exist.