Polariscope is used to test cut or rough gemstones. Allows two polarising filters to observe the structure and optical properties of precious stones or minerals, it can also be used in identifying Moissannite and detecting strain in diamonds. It is used with a thing called a strainless sphere, (that is a glass sphere with no strain lines in it,) or a loupe. It visually shows if a stone is doubly or singularly refractive and its optic sign. It will also show strain and twinning, which will occasionally help to distinguish between natural and man made materials.