This pocket gemological spectroscope in its lightweight yet durable leather case is perfect for when you are on the road and need to make quick purchasing decisions. Bring it with you on buying trips, vacations, or to trade shows. This instrument is so portable, you can easily fit it in your pocket or purse for everyday use. Use this instrument as a confirmation by viewing the absorption spectra of the stone you are examining. Using a white light source and having some knowledge of known absorption spectra will enable you to eliminate possibilities. Pocket Diffraction Grating Spectroscope, with fixed slit & fixed focus. Allows you to read a gemstone's spectral signature. Constructed of stainless steel & black acetol, 55mm long, 14.5mm wide, and weighs 28 grams. Comes in a protective carrying case. The spectroscope is used to analyze light passing through a stone. White light is a combination of all the colors of the visible spectrum: red, orange, yellow, green, blue, indigo, and violet. This is the rainbow we see when light travels through a prism. When white light travels though a stone, one or more of the wavelengths that produce color are absorbed by the gem. The colors that are NOT absorbed are the colors seen when we look at the stone. The wavelengths that are absorbed by the stone are seen in the spectroscope as vertical black lines in the spectrum. Each stone has a unique absorption spectrum (like a fingerprint of the stone) When identifying a stone we look for a spectrum that is characteristic for that stone. The wavelengths that are absorbed by the stone are seen in the spectroscope as verticle black lines in the spectrum. Each stone has a unique absorption spectrum (like a fingerprint of the stone) When identifying a stone we look for a spectrum that is characteristic for that stone.