Because diamond cutting is usually standard, almost no light can pass through the facets of the craft pavilion, when the diamond sample is placed on a piece of paper with black lines, the black lines on the paper are invisible. The same phenomenon can occasionally appear on diamond imitations with high refractive index, such as artificial strontium titanate and artificial rutile, which have no black line and need attention; But for those imitations with low refractive index, you can see the curved black line.

2. Harbin Diamond Identification Experiment

Take a breath on the test sample. If the water vapor covering the appearance of the sample quickly dissipates and is fresh, the sample is declared as a diamond. On the contrary, if the water vapor slowly disappears on the appearance of the sample, it is declared that the sample is an imitation of a diamond. This is because of the high thermal conductivity of diamonds. This is also called "breathing experiment" or "fog experiment". When doing this experiment, if the sample is very small, you need to look at it with a magnifying glass. In addition, this method is not suitable for summer because the evaporation rate of water vapor is greatly influenced by room temperature.

3. Perspective effect

This is a diamond identification method to determine the relative refractive index of transparent round diamond jewelry (especially suitable for jewelry samples with refractive index greater than 1.80). The measurement method is to put the desktop or bottom tip of the sample to be measured down on the paper with handwriting, and see the scale with clear handwriting through the sample. If the scale with clear handwriting is smaller, the refractive index of the sample is larger.

4. Water retention test

Wash the diamond thoroughly to make it free of grease, and then drop water drops on the sample table. If the water droplets can remain on the appearance of the sample for a long time, it is declared that the sample is a diamond. If the water drops disperse quickly, it indicates that the sample is an imitation of a diamond.

5. Thermal conductivity meter test

This method is very common. If the instrument shows a red area and makes a sound when he detects diamonds, it may be diamonds, but the imitation can't be detected by the thermal conductivity meter now, so the diamond identification should be considered comprehensively.

Extended data

Water drop test: This test is based on the oleophilicity of diamond (after rubbing the surface of diamond by hand, it will be found that the diamond looks greasy). Specific practice: You can draw or write on the diamond surface with an oil-based pen, but when you do the same experiment on the surface of other gems or substitute diamonds, the oil stains will be intermittent floating drops. Similarly, there is a folk pencil marking method, which is to wet the diamond sample with water and then mark its surface with a pencil. If there is no pencil mark, it means that the sample to be tested is diamond, otherwise it is other gemstone species.

reference data

Baidu encyclopedia diamond