Abstract: An apparatus for detecting one or more organic compounds in a gem, comprising a probe for irradiating a surface of a gem with near infrared radiation, to generate internal reflections of the near infrared radiation within the gem, wherein the internal reflections are substantially diffuse; a near infrared radiation transmissive conduit for collecting internally reflected near infrared radiation from a surface of the gem, the internally reflected energy comprising components which are diffuse; a spectrometer for analyzing the collected internally reflected diffuse near infrared radiation from the gem, to determine if spectral characteristics indicative of at least one organic compound are present in the gem.

Abstract: 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.

Abstract: Guides to facilitate color grading of faceted gemstones such as rubies and sapphires. Each guide has a series of simulated standards thereon representing a range of grades for a particular class of colored stones and serving as reference points for comparing an unknown therewith in a standardized lighting environment. The guide is constituted by a strip of reflective metal, foil or metallized film sandwiched between a back panel and a top panel having a row of port holes therein, each exposing a reflective zone on the strip. The zone is embossed to create a radial array of wedge-shaped segments, each of which is serrated to define a series of prism-like steps that run from the apex to the base of the segment to provide a pattern simulating the reflective properties of a step-cut faceted stone. Interposed between each zone and its associated hole is a planar optical filter whose coloration is such that in combination with the underlying reflective zone, it creates a respective color grade in the range thereof.

Abstract: A light device for analyzing precious stone body color, comprising a diffused light source in conjunction with indirectly reflected light. Also, method of analyzing precious stones for body color.