Treasures amount of work put into speech (6)
I believe the answer is:
jewels
'treasures' is the definition.
(jewel is a kind of treasure)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for jewels that I've seen before include "Diamonds, rubies, sapphires etc" , "Precious stones or metals" , "Gemstones" , "Diamonds, rubies, emeralds etc" , "Finest examples" .)