The easiest way for ordinary people to identify diamonds is to observe them with the naked eye. The naked eye observation is mainly to observe the "fire color" of diamonds, that is, diamonds can reflect colorful light, which is basically blue light. The more perfect the diamond is cut, the more dazzling the "fire color". The brilliance of imitations with high refractive index will appear stiff and dim.

2. Hardness test

Diamond is the hardest natural substance known, and nothing can mark it. If you can mark it, it's definitely not a diamond.

3. Thermal conductivity test

At the same time, breathe into the diamonds and other similar objects to be debated. If it is a diamond, the water mist condensed on its surface should evaporate faster than other objects, because the thermal conductivity of the diamond is high.

Step 4 observe the reflected light

With a magnifying glass, it can be observed that the waist of the diamond presents a very fine matte shape, and the reflected light shines. This characteristic of diamonds is unique.

Step 5 look at the growing point

Observing under a magnifying glass, there are often grooves and triangular growth points on the crystal face of real diamonds, but there are three kinds of fakes: ① Ordinary glass with alumina is easy to get into the wrong place, because the refractive index and dispersion increase, but the hardness is lower. (2) Imitated with chemically synthesized sapphire and colorless spinel, the hardness is similar, but the refractive index is low and has birefringence, and the double image can be seen under a magnifying glass.

Extended data:

Characteristics of diamonds:

1, chemical properties of diamonds

Diamonds will burn at high temperature to produce carbon dioxide.

Experiments show that the combustion degree of diamond in the atmosphere is 850- 1000, and the combustion temperature in pure oxygen is 720-800. When burning, the diamond emits blue light and a foggy film appears on the surface. When heated to 2000-3000 in the absence of oxygen, diamonds will become graphite.

Diamond is stable to all acids and insoluble in hydrochloric acid, sulfuric acid, nitric acid and aqua regia. Diamonds will be slightly corroded by strong alkali and strong oxidant for a long time.

2, diamond hardness

The Mohs hardness of diamond is 10, which is 100 times stronger than the absolute hardness of corundum with Mohs hardness of 9 and 1000 times stronger than that of crystal with Mohs hardness of 7.

The high hardness of diamond ensures the durability of diamond, which is measured by the wear resistance of diamond. Compared with toughness, the property that it is easy to break under the impact of external force is called brittleness.

3. The color of the diamond

Pure diamonds are transparent and colorless, but if they contain other impurities or have structural defects, diamonds will show various colors. For example, if a diamond contains trace chromium, it will appear sky blue; Elements containing aluminum or nitrogen will appear yellow, and a very small amount of diamonds will turn red, blue, green and purple.

4. Refractive index of diamond

The refractive index of diamond indicates the refraction of light by the medium when it propagates in the medium. The refractive index of diamond is 2.4 17, which is the transparent mineral with the highest refractive index. The higher the refractive index, the slower the light propagates in this medium, the greater the resistance, so the stronger the ability to reflect light.

The bright luster of diamond polishing is mainly due to the high refractive index and strong dispersion of diamond, which produces colorful optical effects.

5, the luster of the diamond

The ability of a gem to reflect light is the luster of a gem. The higher the refractive index, the stronger the luster. In mineralogy, according to the refractive index from high to low, gem luster is divided into four grades, namely diamond luster, metallic luster, semi-metallic luster and glass luster.

Some diamonds also have fluorescence, which is the property that the medium can emit visible light under the irradiation of invisible light. It displays under ultraviolet light, emitting blue, green, yellow, red and other colors.

Reference source: Baidu Encyclopedia-Diamond Identification