Bow ring

by Laura Clarkson
(UK)

I have a gold, diamond and sapphire ring but can't identify the hallmarks. the first is a backwards crescent shape or 'c' with an arrow running through the middle pointing right almost like a backwards bow and arrow. then it has 2500 or 250C or 250G so small i cant work out which it is. then i think there are two letters maybe AL but again they are so small i'm not sure, can you shed any light?

kind regards

Laura Clarkson