The article relates to the issues of optical physics. It is dedicated to the optical destruction of crystals. The main intrinsic mechanism of optical destruction is the mechanism of shock ionization or "electron avalanche". The process of destruction during shock ionization is similar to the electrical breakdown of a dielectric, when free electrons present in a small amount in the dielectric are accelerated by the electronic field of a light wave to speeds sufficient for shock ionization, giving rise to new electrons, which, in turn, accelerate, giving rise to an electronic avalanche. The peculiarity of a breakdown in an optical beam is that it is a breakdown in an alternating high-frequency field. The article also discusses some generalizing criteria that determine the applicability of a crystal for laser technology, and also provides some tips on improving the optical strength of crystalline elements.