Does it say "Artificial Diamonds"? (6)
I believe the answer is:
notice
'does it say' is the definition.
I can't judge whether this defines the answer.
'artificial diamonds?' is the wordplay.
'artificial' becomes 'not' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'diamonds?' becomes 'ice' (slang term for diamonds).
'not'+'ice'='NOTICE'
Can you help me to learn more?
(Other definitions for notice that I've seen before include "Poster; observe" , "Warning - proclamation" , "Public announcement" , "Announcement with information about a future event" , "Advance indication of intention to resign" .)