"Guard well your spare moments. They are like ____ diamonds” (Emerson) (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
uncut
(Other definitions for uncut that I've seen before include "total" , "(Like a book) with pages not trimmed" , "Not shortened" , "Of a film, complete and uncensored" , "Like diamonds, initially" .)