How to identify Chrysoberyl
Chrysoberyl introduction
Figure 1 Various chrysoberyls
Chrysoberyl is named for its unique yellow-green to golden-green appearance and is famous for its special optical effect.
Chrysoberyl is divided into varieties such as chrysoberyl, cat’s eye, alexandrite and alexandrite cat’s eye according to whether its special optical effect exists or not. The most famous one is chrysoberyl cat’s eye.Cat’s eye is deeply loved by people for its silky luster and sharp eyeliner. In Asia, cat’s eye gemstones are often regarded as a symbol of good luck. People believe that it will protect the owner’s health and avoid poverty. Alexandrite is even known as “emerald in the daytime and ruby in the night”. In the West, chrysoberyl is one of the five famous gemstones.
How to identify
Only the gemstones whose all the following data meet the identification characteristics of chrysoberyl are chrysoberyl.
- Refractive index and birefringence of chrysoberyl
The refractive index and birefringence of chrysoberyl are measured using a gem refractometer (Figure 2).
The refractive index (Figure 3) is: 1.746~1.755, and the birefringence is: 0.008~0.010.
Figure 2 Gemstone refractometer
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Figure 3 Refractive index readings |
- Optical characteristics of chrysoberyl
The optical characteristics of chrysoberyl are mainly detected by a gem polariscope (Figure 4).
The optical characteristics of chrysoberyl are: heterogeneous(four times light and dark under a gem polariscope), biaxial crystals (Figure 5), and positive optics (measured by a gem refractometer).
Figure 4 Gemstone Polariscope |
Figure 5 Biaxial crystal interference pattern |
- Chrysoberyl’s Pleochroism
Chrysoberyl has trichroism, which is measured by a dichroscope(Figure 6). The strength of the trichroism of chrysoberyl and the color change depend on the color and color depth of the chrysoberyl itself. The common trichroism of chrysoberyl (Figure 7) is: yellow, brown, and green.
Figure 6 Dichroscope |
Figure 7 Pleochroism of chrysoberyl |
- Absorption spectrum of chrysoberyl
The absorption spectrum of chrysoberyl is measured by a gem spectroscope (Figure 8). Different chrysoberyls have different absorption spectra depending on the impurities they contain. Generally speaking, chrysoberyl has a strong absorption band centered at 445nm (Figure 9).
Figure 8 Prism gem spectroscope and diffraction grating spectroscope |
Figure 9 Absorption spectrum of chrysoberyl |
- Density of chrysoberyl
The density of chrysoberyl is measured by a density balance (Figure 10). The density of chrysoberyl is 3.73 (± 0.02) g/cm3.
Figure 10 Density balance
- Magnification inspection
Magnified features of chrysoberyl can be checked by a gemological microscope (Figure 11).
Figure 11 Gemstone microscope
Magnified inspection usually reveals gas-liquid inclusions (Figure 12), fingerprint-like inclusions (Figure 13), filamentous inclusions (Figure 14), mineral inclusions (Figure 15), etc.
Figure 12 gas-liquid inclusions
Figure 13 fingerprint-like inclusions
Figure 14 filamentous inclusions
Figure 15 mineral inclusions