I love this little ring by H&M, I have the gold version with the salmon coloured stone myself.
Available online: CLICK
These two are from River Island, I simply love that deep blue colour and it looks amazing on (I tried it on) and the second is as close to the YSL arty ring as highstreet and pocket money goes.
Both available online: CLICK
The above are all topshop! There seems to be a theme to the rings I like in topshop at the moment, I was in there today and I did buy myself a small ring for once for £5! I walked out of there a very happy Bunny.
All available online: CLICK