Abstract: Some researches show that there are plentiful micro-inclusions in dark colour sapphires from Shandong Province. Through optical analysis, it indicates that scattering of micro-inclusions in the sapphire to light reduces the intensities of transmitted and internal reflected light, resulting in decreasing in transparency and brilliance of colour. In heat treated Shandong sapphires, the micro-crackes are more devoloped, and scattering of structural micro-inclusions to light are probably one of reasons why heat treatment on Shandong sapphire is not effecient.