Something Zac from JerryRigEverything says in nearly every YouTube Video. He is known for literally destroying phones for a
living with various durability tests. Refers to the Moh's Scale of Hardness, and how
strong certain cell phone glass is.
Most cell phone glass scratches at a level
6 on the Moh's Scale of Hardness with more scratches being visible with a level 7 '
pick'.
"Glass is glass, and scratches at a level
6 with deeper grooves at a level 7".