Based on a study of physical and optical properties and chemical contents of ruby and sapphire from Heilongjiang Province, together with a preliminary discussion on the color_causing factors of these two minerals, it is believed that ruby and sapphire in Heilongjiang Province can be divided into red and blue series consisting totally of twelve colors. Their physical and optical properties and chemical contents show remarkable differences. Spectral analysis shows that the color of ruby is caused by the color_causing elements nickel, chromium and iron, whereas the color of sapphire by the color_causing elements iron and titanium. The variations of their color shading and tone result mainly from the iron content and Fe~(3 )/Fe~(2 ) ratio.