Diamonds and cool stuff (3)
I believe the answer is:
ice
I believe this is a double definition.
'diamonds' is the first definition.
(slang term for diamonds)
'cool stuff' is the second definition.
(ice is cool or cold)
'and' acts as a link.
(Other definitions for ice that I've seen before include "Diamond" , "Diamonds, colloquially" , "engine" , "Winter formation" , "dessert" .)