The visible absorption spectrograms of 32 jadeite jade samples were measured by MPV-Ⅲ microphotometer, and their three-impulse values were calculated. On such a basis, the concept of color difference in even color space is put forward. By calculating NBS values of the samples, the color differences of the samples were analyzed quantitatively. It is shown that the quantitative calculations of color differences can present true colors of different samples and are different from the metamerism indexes. Therefore, this technique is a valuable means for identification of green jadeite jade and can play a very important role in gem identification.