A "refractometer" is a measuring instrument to measure the refractive index of a liquid (solid), applying the principle of light refraction. There are various models that have the sugar content (Brix) scale, the salt concentration scale, etc., based on the refractive index. A hand-held refractometer is the most basic type of refractometer and enables anyone to perform measurements with ease. The operator simply applies a sample to the prism and views the measured value through the eyepiece. A digital refractometer assists the operator in performing measurements accurately and easily. The measured value is displayed digitally with one touch of the START button. The digital readout saves the user time and trouble reading the measured value as compared to the measurement reading required for analog hand-held refractometers and analog Abbe refractometers. This handheld digital refractometer has four scales: Brix, Baume, water, and Refractive index.