(8) With hair inspection: Put the crystal on a hair, the human eye can see the double shadow of the hair through the crystal, it is natural crystal, mainly because the crystal has birefringence.
Photovoltaic glass definition and classification
Blue reflective glass is becoming increasingly popular in modern architectural designs due to its stunning visual impact and functionality. This type of glass is coated with a thin layer of metallic oxide, giving it a reflective finish that creates a sleek and contemporary look.