This handy, pocket-sized Polarized Stress Tester is ideal for checking stress patterns in liquid crystals, plastics, and gemstones. The Polarized Stress Tester shows fracture marks and flaws not visible with the naked eye or many magnifiers. Additionally, the Polarized Stress Tester is useful in checking the hardness formation of lenses, as it brings out the Maltese cross pattern visible only in properly hardened lenses. The stress tester’s dimensions are 3" x 3" when folded and 3" x 6" when open. A black carrying case is included.