Yellowish, bluish or colourless precious stone (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
topaz
(Other definitions for topaz that I've seen before include "Precious stone - dark yellow colour" , "valuable item" , "Precious stone - American hummingbird" , "Shade of yellow -- gem" , "Type of gemstone" .)