never heard of this stuff but ... can they make eye glasses from it ?
Hardness and durability is the main reason for Apple’s interest in sapphire glass. On the hardness scale, the only material tougher than sapphire is diamond. What this means is that it is immensely scratch resistant in a way that no other comparable material is — both in terms of “flaw initiation” (i.e. when it starts to scratch) and toughness (when it cracks).
Anything is possible but the cost of trying to make lenses out of material almost as hard as diamond would be prohibitive.
Transparent Aluminum (Aluminum Oxide)
You might not like the price or the weight for your eyeglasses. Double the density compared to the same index of refraction.
http://www.eyeglasslenses.com/content/knowledgebase/kb_materialsandtypes.asp
http://www.mt-berlin.com/frames_cryst/descriptions/sapphire.htm
Really? Never heard of sapphire?