A deep red transparent precious variety of corundum (4)

I believe the answer is:

ruby

(Other definitions for ruby that I've seen before include "Gemstone comprising mainly aluminium oxide" , "Jack perhaps" , "Precious red gem" , "Gemstone - shade of red" , "Girl's name - colour" .)

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.