What is Chelsea filter?

Chelsea filter: It was originally used to identify emeralds, so it is also called "Emerald filter". Because of its wide use, it is sometimes referred to as "filter" in some Chinese documents. The earliest first-generation Charles color filter is made of a special dark yellow-green adhesive film, which is sandwiched in a protective glass sheet and packaged in a circular plastic shell that can be rotated in and out. The effect of differential dyeing is also obvious, but the disadvantage is that this film will gradually lose its dark yellow-green color after long-term use, and will lose its optical characteristics of color filtering after a period of use. Some friends who use color filters don't know that the color filters have been decolored, but they still use decolored color filters, which will mistake the dyed gems for natural purchases. So the first generation Charles filter was gradually eliminated in the 1980s, and the second generation Charles filter appeared at the same time. The second generation Charles color filter consists of two pieces of glass coated with color filter film, which has a longer service life than the first generation, but generally speaking, it will gradually fade after long-term oxidation and heating. With the development and progress of science, some gem associations in Britain have developed a special colored glass, which is a special color filter glass, consisting of a special orange lens and a special blue lens. It can detect the dyeing phenomena of all kinds of green and blue gems, especially the fake skin color of dyed Hetian jade and the fake red blood of antique jade. This is a new generation of Charles filter, named: the third generation of Charles filter (Chelsea Colour Filter III). Because of its special lenses, it is made of glass that never fades, so we don't have to worry that one day we won't see the dyed gems. Moreover, this special glass itself deepens the color filtering effect, which can also be seen for some very shallow dyeing. In addition, a set of 30 times wide-angle optical gemstone magnifying glass has been added, which is more convenient for collectors to observe the internal structure of jadeite and gemstones, the quality of carving technology and so on. Optical characteristics: transmitting crimson light and a small amount of yellow-green light, absorbing green light and other colors. Because it has the characteristics of transmitting colored light and absorbing colored light, it provides great help for us to identify various dyed green gems and blue gems, especially the dyed skin of Hetian jade and the dyed skin of antique jade, which saves collectors a lot of opportunities to be fooled.