Diamond or ruby, eg (8,5)
I believe the answer is:
precious stone
I believe this clue is a double definition.
'diamond' is the first definition.
(I've seen this in another clue)
'ruby eg' is the second definition.
(ruby is a kind of precious stone)
(Other definitions for precious stone that I've seen before include "rock" , "Diamond, perhaps" , "Gem or jewel" .)