Ruby has a strong dichroism (that is, it is obvious), and four of the red gems similar to it are "no dichroism". This way we can use dichroism to distinguish. Any gemstone with no dichroism is definitely not a ruby, a valuable Burmese jade, then, what is dichroism? What does it use to observe? How to observe it? "Dichroism" is an optical phenomenon, that is, the change in the color of a gemstone. A dichroic gem, which looks at it from different directions, will show different colors. However, this color change is not obvious and can only be seen with the naked eye. Observing dichroism generally uses an instrument called a dichroic mirror. This is a small cylindrical tube with a length of about 50 mm and a diameter of about a few ten millimeters. The tube has a small square hole at one end and an eyepiece at the other end. Keep your eyes close to the eyepiece, and the small square hole is facing the bright spot (such as the sky). You can see that there are two rectangles in the tube that are juxtaposed together. When using, put the gemstone with a pair of tweezers, close to the small square hole of the dichroic mirror, expensive natural jade, watch the bright spot, if the color of the two bright frames is "identical", it means that the gem "no color" Sex." If two side-by-side bright boxes "different colors" indicate that the gems "have dichroism", the greater the difference in color between the two bright frames, the stronger the dichroism. For example, placing the ruby ​​in front of the small square hole of the dichroic mirror reveals two bright boxes: one is dark red and the other is yellow red, which is very different, indicating that the ruby ​​has strong dichroism.