Already exists under the brand name ALON (Aluminium Oxynitride).

It's hard as hell for a transparent ceramic, obvious military applications but useful in other places as well.

Transparent aluminum exists? Wow, that's cool!

Calling it "transparent aluminum" is perhaps a tad misleading as it's only about 30% aluminum. Still very cool though.

So ALON? https://en.wikipedia.org/wiki/Aluminium_oxynitride