Tiger's eye is also known as silicified crocidolite whose raw mineral is blue asbestos formed by later replacement of SiO₂. It is named for its similarity to trees in color and texture. The previous researchers have already preliminarily studied color genesis of tiger's eye. As tiger's eyes with different colors have various gemological characteristics, the authors made investigations to find the relationship between these characteristics, such as the relationship between the structure and the relative density, that between the color and the mineral components as well as chemical composition, and that between the structure and the special optical effect. In combination with previous achievements of color genesis of tiger's eye in specific producing areas both in China and abroad, the authors hope to draw a further conclusion. Such means as polarizing microscope, infrared spectrometer, X-ray diffraction (XRD) and X-ray fluorescence spectrometry were used to analyze the microstructures, chemical compositions, mineral components and chemical elements compositions of the samples of tiger's eyes. The results show that the four samples have fiber structures. The analysis of infrared spectrometer and X-ray diffraction (XRD) suggests that the samples consist of quartz, whose colors have nothing to do with quartz. Based on X-ray fluorescence spectrometry, the authors inferred the coloring mechanism. Specifically, the samples' colors are caused by iron precipitates among grains of quartz with fiber structure, and their color variations are related to various degrees of silicification of crocidolite. Among these samples, the blue sample has the silicification at the minimum level with a lot residual blue asbestos; the yellow one has the moderate silicification, in which aluminum is supposedly the secondary coloring element; the red one has the highest degree of silicification, which presents reddish brown color with a lot of iron precipitates. The green sample is dyed over a short period of time after acid pickling, in which the attachment of the dye is the same as that of the nonferrous mineral in other natural samples.