Can someone recommand a good place in İstanbul for buying a golden ring?

Dear Kartal

Grand Bazaar

http://www.turkeytravelplanner.com/WhereToGo/Istanbul/Sights/Beyazit/GrandBazaar.html

You can also find jewellers in shopping malls.

here is a list

http://en.wikipedia.org/wiki/List_of_shopping_malls_in_Istanbul

good luck.

It's really no problem to find a jewellery shop in Istanbul They're all over the place!

There're a lot in Kadıköy as well.

check this one
www.piriltialyans.com

I've been in their factory

thanks everybody!