Diamonds are luminous, and after being irradiated by sunlight, they can emit light blue phosphorescence at night. X-ray irradiation emits sky blue fluorescence. The chemical properties of diamond are very stable, and it is not easy to dissolve in acid and alkali at room temperature, and acid and alkali will not affect it.

Most diamonds are octahedron, rhombic dodecahedron, tetrahedron and their aggregates. Total internal reflection: critical angle: 24.5.

Diamond color grades: D 100 extremely white, E 99, F 98 excellent white, G 97, H 96 white, I 95 yellow white (brownish gray), J 94, K 93 light yellow (brownish gray) white, L 92, M 9 1 light yellow (brownish gray). N & lt90 yellow (brown, gray)

Clarity classification is based on the position, size and quantity of inclusions. From high to low, it can be divided into FL, IF, VVS 1, VVS 2, VS 1, VS 2, Si 1, Si2, Si3, P 1, P2, P3. Observe the diamond carefully under a ten-fold microscope. FL-"perfect", perfect. If there is no flaw inside and outside-under the magnifying glass of ten times, there is no flaw inside. Under the magnifying glass of ten times, there are only slight flower marks on the surface, vvs 1, vvs2-"very, very fine", very, very small. There are defects that are difficult to see under a magnifying glass of ten times. The definition of VVS 1 is higher than that of VVS2. VS 1 and vs 2-"very thin", very small. Defects can be seen under a magnifying glass of ten times, but it is difficult for the naked eye to recognize them. The definition of VS 1 is higher than that of VS2. Si 1 and si2- "slight inclusions", small flaws, which may be visible to the naked eye. I 1, I2, i3-"Imperfect" is flawed and visible to the naked eye.