Gemstone and ring given to friend (4)
I believe the answer is:
opal
'gemstone' is the definition.
(opal is a kind of gemstone)
'ring given to friend' is the wordplay.
'ring' becomes 'o'.
'given to' says to put letters next to each other.
'friend' becomes 'pal' (pal is a kind of friend).
'o'+'pal'='OPAL'
'and' is the link.
(Other definitions for opal that I've seen before include "Opaque gem" , "Many-coloured gem" , "Glassy gemstone" , "Quartz-like gemstone" , "Shimmering stone" .)