Emerald or amethyst (3)
I believe the answer is:
gem
I believe this clue is a double definition.
'emerald' is the first definition.
(I've seen this in another clue)
'amethyst' is the second definition.
(I've seen this in another clue)
(Other definitions for gem that I've seen before include "Diamond, ruby, or emerald" , "Kindness; comfort (German)" , "one of the Cairngorms?" , "Valued person; jewel" , "Half of 7 [SIGN OF THE ZODIAC]" .)