The principle of DICOROIC GLASS is to place a colorless calcite (Icelandite) in it to split the light into two vertically oscillating lights, and observe the colors of the two lights separately through DICOROIC GLASS.

The end of the lower right corner of DICOROIC GLASS is to be connected to the observation object, and the other end is to be connected to the eye; there is a magnifying glass at the end of the object to observe the observation object more clearly.
DICOROIC GLASS is the most commonly used instrument to verify birefringence. Just like its name, DICOROIC GLASS is an instrument used to test whether gems have dichroism. Since only birefringent gemstones have dichroism, if the dichroism can be tested, it can be proved that the tested gemstones are birefringent gemstones. The opposite is not necessarily true. Dichroic samples cannot be detected. There are two cases. It may be a single-refraction gemstone, or although it is a birefringent gemstone, its dichroism is too weak.
When normal white light passes through a birefringent gem, it will be broken down into two beams of light oscillating perpendicular to each other. Due to the principle of dichroism, the colors of the two beams may be different, but they mix together and enter the human eye, which is the gem’s Color, human eyes have no way to distinguish the two beams, so we need to use DICOROIC GLASS; the calcite in DICOROIC GLASS is the mineral with the largest birefringence effect in nature, which separates the two beams of light from the gemstone again Open, and then use the optical reflection guide in DICOROIC GLASS to project the two beams of light to two different areas, and the user can confirm whether the gemstone has Dichroism can also infer whether a gemstone has birefringence.
To sum up briefly, observe the gemstone through DICOROIC GLASS, you will see two small windows, which represent the same area on the gemstone, but the color of the light in different oscillation directions. If the colors of the two windows are different, it can be seen that the gemstone has two Chromaticity. The manufacturer of DICOROIC GLASS tells you that sometimes, even if you observe a single-refraction gemstone, due to light reflection, scattering or other reasons, the user will feel that the colors of the two windows are slightly different. This situation will make the single-refraction gemstone and weak dichroism There is little difference between sexual birefringent gemstones, and it is difficult to distinguish, which is also a limitation of the instrument itself.
Therefore, if you observe that the colors of the two windows are strongly different, it can be confirmed that the gemstone has dichroism. The manufacturer of DICOROIC GLASS tells you that if the color difference is extremely small, you do not need to strongly believe that it is dichroic, and then use other methods to confirm the gem's color. Double refraction is fine.