Finishing touch: glass bowl adorned with raised diamonds (4,2,5)
I believe the answer is:
coup de grace
'finishing touch' is the definition.
(I've seen this in another clue)
'glass bowl adorned with raised diamonds' is the wordplay.
I cannot really see how this works, but
'raised' could be 'up' (similar in meaning) and 'up' is present in the answer.
'diamonds' could be 'd' (abbreviation in bridge say) and 'd' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for coup de grace that I've seen before include "Decisive stroke" , "Killer" , "Merciful release" , "Finishing blow to put out of pain" .)