Being local to me I've been to the Jewellery Qtr a couple times. Maybe it's just me but I found buying a dimond ring an absolute nightmare, buying an engagment ring for my ex was the worst. You don't wanna get ripped off or buy a shitty diamond.
Maybe I'm wrong but there seemed to be a lot of tat in the Jewellert Qtr and it felt like a lot of shops would be offering you something that wasn't what they said it was.
I was told that out of the 100's of shops in Brum only 5 or 6 were certified jewellers or something that carry a particular coat of arms above their door. These particular shops were the reputable ones you can buy with confidence from. I ended up buying from one of them but paid a premium for doing so.
Then again it could all be a load of bollox, maybe Chiefgrover could offer a bit more advice.