Microscopes are used to see very highly magnified areas on a part. Micro examination determines the microstructure, inclusion, and mode of heat treatment given to the component. It also gives information about the presence of micro-cracks, welding, structural changes due to working etc. It is also common to examine for metallurgical anomalies such as excessive grain growth, etc. Many routine tests such as grain size determinations are performed in conjunction with micro-examinations. Micro examination is performed on samples either cut to size or mounted in a resin mold. The samples are polished to a fine finish, normally one micron diamond paste, and usually etched in an appropriate chemical solution prior to examination on a metallurgical microscope. Unetched micro-examination is done on the polished surface after etching the micro-piece with suitable chemicals under bench microscope, at magnification from 100 to 1000.