Diffuse reflectance spectroscopy using near infrared and mid infrared
radiation is used to detect the presence of organic chemical compounds in
gems. Suitably, diffuse reflectance infrared Fourier transformation
spectroscopy is employed to detect the presence of organic compounds in
gems using mid infrared and near infrared radiation. The apparatus uses
an integrating sphere or integrating cylinder with a probe that acts as
both a source of near infrared radiation and a detector of reflected
diffuse internal energy from the gem. Alternatively, the integrating
sphere or integrating cylinder is replaced with a reflective fluid which
surrounds the gem and causes total internal reflection.