1. Cathodoluminescence instrument: synthetic diamond: similar to ultraviolet fluorescence distribution characteristics, different growth regions show different fluorescence bands.

Natural diamonds: most of them are absorption lines of 4 15.5nm.

2. Ultraviolet fluorescence: synthetic diamonds: usually no fluorescence at long wavelength, yellow-green and orange-yellow fluorescence at short wavelength, "Maltese cross banding" phenomenon, and natural diamonds with obvious phosphorescence: mostly irregular.

Because when natural diamonds grow, the environment will always change, but the growth environment of artificial diamonds is unchanged.

3. Infrared spectrum: synthetic diamond: 1 130 absorption band.

Natural diamonds: absorption bands of light beams 1 176 and 1282.

4. Conductivity: Synthetic diamonds: Some may have conductivity or thermal conductivity.

Natural diamonds: Except for blue diamonds, they are semi-conductor, non-conductive and non-magnetic.

5. Others: such as abnormal birefringence.

The identifying characteristics of synthetic diamonds—

6. Crystallization habit: Synthetic diamonds are usually cubic, octahedral and a combination of the two.

Natural diamonds are usually octahedral, rhombic dodecahedron and their aggregates, and there are also common triangular lamellae twins.

7. Color: Synthetic diamonds are often yellowish brown, and often turn blue, orange, pink, brown and golden yellow after irradiation.

98% natural diamonds are colorless-light yellow series.

8. Surface and internal texture: synthetic diamond: dendritic or cross-shaped texture can be displayed.

Natural diamond: triangular dents or triangular seats are common on the surface, and texture related to structure is often displayed inside.

9. Magnified observation: synthetic diamond: seed crystal and its phantom area, various forms of metal inclusions.

Natural diamonds: no metal impurities.