Can not be exposed to direct sunlight, if exposed to the sun for a long time, it will change color. Resins are now collected commercially, such as hard resins produced in New Zealand. Baltic amber is used for jewelry and hard resin for decoration. Spencer et al. recently re-studied these coba resins from New Zealand based on the samples provided by the Institute of Gemological Society of New Zealand and the samples obtained from New Zealand coal mines. In his research, the most important gemological discovery shows that the ether introduced in classic gemological books to identify cobalamin and amber is not ideal for kauri, that is, some kauri is actually insoluble or only slightly soluble in ether. Drop a drop of ether on these insoluble Coba resins, and there is no reaction or slight reaction after 30s; However, after dropping a drop of alcohol on these Copa resins (including 25Ma resins), all of them will react in alcohol after 30s: the surface will become sticky or opaque, while the real amber will not react at all when dropping alcohol, indicating that it is insoluble in alcohol. Copa resin is also easy to produce dissolution reaction similar to alcohol in glacial acetic acid, but glacial acetic acid will produce irritating smell, which may be harmful to alcohol. Human body burns, so it is not suitable as a gemological test method. In addition, his experiments also show that the reaction of natural Copa resin under ultraviolet fluorescence is unstable, which is difficult to be used as an identification basis to distinguish amber from Copa resin.