In some embodiments, processes for testing for structural flaws in sapphire parts such as display cover plates used in the manufacturing of electronic devices are disclosed. A process may include transmitting a destructive acoustic signal onto a sapphire part, and determining whether the sapphire part failed in response to the destructive signal. The destructive acoustic signal may include a Rayleigh acoustic wave, wherein the destructive acoustic signal breaks the sapphire part if the sapphire part has a surface flaw larger than a specified size. In this manner, only sapphire parts that can withstand the destructive acoustic signal are used in manufacturing of the electronic device.