Article given to yours truly -- your old stone, a precious stone (8)
I believe the answer is:
amethyst
'a precious stone' is the definition.
(I've seen this before)
'article given to yours truly your old stone' is the wordplay.
'article' becomes 'a' (indefinite article).
'given to' is a charade indicator (letters next to each other).
'yours truly' becomes 'me'.
'your old' becomes 'thy'.
'stone' becomes 'st'.
'a'+'me'+'thy'+'st'='AMETHYST'
(Other definitions for amethyst that I've seen before include "Purple quartz used in jewellery" , "Type of quartz" , "Bluish-violet 3" , "Purple gem" , "Violet-coloured stone" .)