Abstract: There are 2110 cm^-1 and 1980cm^-1 characteristic absorption double peaks of diaspore or absorption peak of other inclusions in the infrared spectrum of natural ruby. There are three inherent characteristic absorption peaks of 3184, 3232 and 3310cm^-1 in the infrared spectrum of flame fusion grown ruby which has been heat treated at 1100°C. This is the normal principals acquired by the author who has measured infrared spectra of many samples in recent two years.