2. Magnifier: It is one of the instruments for magnifying and observing gems. The most commonly used magnifying glass is 10 times, and there are several kinds of magnifying glasses with 20 or 30 times. Magnifier is a key tool and necessary thing for gemologists, and it is easy to carry. It can be used to identify the variety and authenticity of precious stones.
3. Dichroic mirror: Some gems are multicolored, and the best instrument to observe the multicolor of gems is the dichroic mirror. Dichroic mirror is a kind of optical instrument with reasonable structure, low price, compact and simple. The dichroic mirror uses a suitable transparent colorless calcite (Iceland spar) diamond. Because Iceland spar has high birefringence, the instrument can separate two plane polarized light rays passing through the gem.
It is required that single crystal gemstones with transparent colors can detect polychromatic colors, while jadeite cannot detect polychromatic colors. Dichroic mirror is mainly used to distinguish ruby from spinel and red-purple tooth black; Distinguish blue spinel from blue tourmaline; Distinguish sapphire from blue synthetic spinel.
When detecting a gem with a dichroic mirror, you must keep turning the gem until the two colors with the biggest difference appear on the window. For the determination of trichromaticity of gemstones, we must carefully and repeatedly test. Seen from three different directions, three colors seem to be three colors. Note during testing: the distance between eyes, dichroic mirror and gem sample should not exceed 2-5mm.
4. Refractometer: Refractive index is an important optical constant of transparent gemstones and the main basis for identifying gemstones. There are two main methods to measure refractive index: one is direct measurement and the other is refractometer measurement; The other is relative measurement, which cannot be immersed in liquid. Refractometer is made according to the principle of total reflection of light.
The commonly used refractometer is only suitable for gems with refractive index of 1.36- 1. 1. The calculation method of the refractive index (n) of gemstones is that the ratio of the propagation speed of light in air (V 1) to that in gemstones (V2) is a constant, that is, N=V 1 /V2. An isotropic gem in which light propagates with constant propagation speed and equal refractive index is called single refractive index.
Anisotropic gemstones have two readings in the refractometer, and the difference between the maximum and minimum refractive index values is called birefringence. Refractometer is one of the most commonly used instruments for gemologists. It is small in size and convenient to use. He can not only measure the refractive index of faceted gemstones, but also measure the refractive index of globoidal gemstones through point measurement.
Extended data:
Shopping guide:
1 first of all, we must objectively prevent buying fakes.
Although the GEM is small, it is valuable. A humble gem can sometimes be compared with the price of a color TV, a car or even a Boeing plane. If you buy fake goods, the loss is huge. In addition to mastering certain theoretical knowledge subjectively and accumulating rich practical experience, it is best to buy fakes in regular exclusive jewelry stores.
In order to improve the reputation of enterprises and safeguard the interests of consumers, some domestic jewelry manufacturers and shops take the initiative to provide consulting services for consumers. For example, some jewelry stores hire jewelry experts to answer various questions for consumers on the spot and identify jewelry for free on the spot. Many villages in China, including small and medium-sized villages, have such service measures.
2. Carry basic tools for identifying gems.
Even if you go to a state-run store to buy jewelry, you can't take it lightly. In order to improve the accuracy of identification, you must carry the most basic tools, such as magnifying glass and spotlight flashlight. Consumers have no difficulty in carrying these tools.
With the help of a magnifying glass, we can observe the brightness and damage of a gem, thus determining the quality of the gem and identifying the variety of the gem. It is best to use a magnifying glass with a magnification of 10 for gem identification, and it is even better to prepare a magnifying glass with a magnification of 20. You can observe the transparency of gems with a spotlight flashlight.
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