Sapphire
glass is extremely hard and is used in some high - end watches, but it can be heavy and is more expensive than Gorilla Glass — though researchers are trying to reduce both its weight and its
glass is
extremely hard and is used in some high - end watches, but it can be
heavy and is more expensive than Gorilla
Glass — though researchers are trying to reduce both its weight and its
Glass — though researchers are trying to reduce both its weight and its cost.