| 摘要 |
PURPOSE:To provide a diamond color measuring device capable of performing an objective and highly accurate measurement, wherein the spectrum of light transmitted through a diamond is measured and the evaluation of color grade of the diamond is made on the basis of three excitation values X, Y and Z of color. CONSTITUTION:The light coming out of a spectroscopic section 23 is applied to a photomultiplier tube 48 and is changed into an electric signal of a level proportional to the intensity of the light. In a measuring section 49, the spectral wavelength of the spectroscopic section 23 is controlled to provide a spectrum of the light transmitted through a diamond D and, at the same time, a feedback signal 50 is produced on the basis of a reference light detected in synchronism with the operation of a chopping mirror 21 to vary the negative high voltage imposed on the photomultiplier tube 48 thereby to effect an automatic control of the sensitivity. In a computing section 51, three excitation values X, Y and Z of color are obtained from the spectrum received by the measuring section 49. It is possible to promptly and objectively know the color grade D of the diamond D by comparing the three excitation value X, Y and Z with those in a color grade table obtained beforehand in relation to the color grades of known diamonds. The computing section performs a further operation to permit an easy recognition of the color grade of the measured diamond. |
