Holmuium Oxide is a laboratory grade solution used as standard for verifying the accuracy of wavelength of a spectrophotometer. The international pharmacopis guidelines provides for use of Holmium oxide for verifying the wavelngth. The Holmium oxide is permanently locked and selaed in quartz cuvette of a spectrophotometer. Holmium oxide works in a stress free propriety NIST design with wavelengths 279nm, 361nm, 454nm, 536nm, 638nm.