“Ceramic Glass is very close to being like Transparent Aluminum in my books.”
Mohs hardness:
Saffire 9
GG Ceramic 7
Aluminum 2.75
transparent aluminum is different.
Hardness and Durability: It is significantly harder than conventional glass, with a rating of around 9 on the Mohs scale of mineral hardness, just below diamond. Additionally, it displays excellent scratch resistance and durability.
https://modern-physics.org/transparent-aluminum/