Diamonds, which captivate the eyes of many people, are either natural or synthetic. Natural diamonds are mined from the earth and synthetic diamonds are artificially made. In recent years, it has become extremely difficult to judge
whether a diamond is of natural or synthetic origin by using conventional gemstone appraisal tools and equipment, raising the need for new judgment methods. One such new method utilizes a spectrophotometer. This article introduces measurements of the reflectance and
transmittance spectra of various natural gemstones including diamonds using UV-visible spectrophotometry and Fourier transform infrared spectrophotometry.