Gems and precious metals (6)
I believe the answer is:
jewels
'gems and precious metals' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for jewels that I've seen before include "Precious stones or metals" , "Precious stones and minerals" , "Gemstones" , "Diamonds, rubies, emeralds etc" , "Diamonds, rubies, sapphires etc" .)