In order to gradually narrow down the list of minerals that appraisers may suspect, the above 25 minerals are divided into transparent and opaque categories according to transparency; According to the color, it can be divided into colorless, red pink, blue purple, green, yellow, brown orange and so on. Identification can be based on the transparency and color of unknown minerals or finished products, and the corresponding identification table can be viewed by comparison. For example, there are two kinds of opaque jewelry with different green stripes, almost certainly malachite, dyed agate, dyed striped marble, green fiber mineral, glass or plastic. Therefore, for appraisers, the transparency and color of unknown jewelry have special significance. It should be noted that magnifying glass and spotlight pencil flashlight are essential for naked eye observation.

(2) refractive index

This is the second step of observation, and its purpose is to reduce the number of suspected minerals after estimating the refractive index range of the measured jewelry. Appraisers can roughly estimate the refractive index range of this mineral from the luster, and the stronger the luster, the higher the refractive index. Jewelry with diamond luster, whose refractive index exceeds the highest range of refractometer scale (1.80); The refractive index of glass luster is 1.8- 1.5. Compared with jewelry with known refractive index, the similarity of luster can quickly help appraisers to classify unknown jewelry according to refractive index or luster.

Waxy, greasy and shiny jewelry generally has a poor polished surface, and silky luster indicates that there may be many real inclusions.

(3) Color brightness

There is a difference between bright and dark colors of jewelry. For the purpose of recognition, three colors are artificially divided into bright, medium and dark according to the brightness of colors. For example, only emeralds, emeralds and garnets are bright green gems; Dyed or inlaid combination gems. When the flat top of a transparent plane gem is prevented from rotating on white paper, if a red ring appears at the waist of the gem, it implies that the top is a double assembly of garnet. It emits red light from dark fresh sapphire, which can be considered as synthetic spinel or zoisite variety Tanzanite.

(4) dispersion

The purpose of this observation step is to distinguish some gems and substitutes with strong dispersion observed by naked eyes, such as diamonds, zircon, sphene, garnet, rutile, artificial rutile, titanium gills (titanium gills) and some glasses from other gems.

(5) cleavage

Only diamonds, topaz, spodumene and feldspar have obvious cleavage.

(6) Specific gravity

Beginners should often practice hand balancing specific gravity. The method is to compare the minerals with known specific gravity with unknown jewelry and minerals by hand, and get a basis for estimating the specific gravity range. If necessary, put it into a liquid with appropriate specific gravity for actual measurement.

(7) Double shadows

With naked eyes or a low-power magnifying glass, we can see that there is a ghost (edge) in the adjacent part of the gemstone corresponding to the carving surface, and there are sphene, zircon, olivine, tourmaline and artificial rutile with strong ghost properties.

(8) Hardness

If the finished gem has round edges and polishing differences, it shows that its hardness is low. And some cheap materials such as synthetic corundum, if the polishing speed is too fast, will cause poor polishing quality, and "heating" is also its characteristic in the process of re-polishing.

(9) Polychromaticity

When turning the gem, the naked eye can see that the multicolored original stones are spodumene, andalusite, tourmaline, zircon, ruby, sapphire and metamorphic rock. Rare gems include topaz, cordierite, zoisite and epidote.