| 摘要 |
PURPOSE:To make it possible to accurately judge the color grade of diamond, by aranging a photodetecting element so as to direct the light receiving surface thereof to the jewel to be measured while providing a small orifice to the center of the photodetecting element. CONSTITUTION:A photodetecting element of which the light receiving surface 2a is directed to diamond A is arranged under a table 1. A small orifice 3 with a diameter of about 1mm. is provided to the center of the photodetecting element 2 and the diamond A is placed directly above the small orifice 3. A light emitter 4 for irradiating the diamond A through the small orifice 3 is provided directly under the small orifice 3 in the opposite side relative to the light receiving surface 2a of the photodetecting element, that is, below the photodetecting element 2. By this mechanism, the color grade of the diamond can be accurately judged. |
