Abstract: The wavy lines on the polished surface of jadeit jade are visiable to the naked eye or observation under magnification. There are three causes that produce microwavy line. Firstly, the hardness is different on different crystal faces of the jadeit and on different directions of crystal face after polishing. Secondly, well-developed cleavages can result in peeling off along the cleavages which parellel the polishing direction when jadeit jades are polished. Thirdly, the other minerals with different hardness from jadeit can produce microwavy lines on the polished surface of jadeit jade. The microwavy line and flash on the crystal face are the main characters of jadeit jade, but they belong to different categories. Understanding the mechanism and characteristics of microwavy line on polished surface of jadeit jade can seperate iadeit iade from other kinds of jade and imitations quickly and effectively. Microwavy line also is an important indication in identification of A, B, C of jadeit jade and film-plating jadeit jade. The observation of micro-wavy line is very simple and easy.