for Guys: how do you know it's the perfect engagement ring for your girl?

Seems like you are getting all answers from women, but they are worth their weight in gold.(No pun intended). We are(usually) on the receiving end of this, and lord knows we know what we want(at least between a couple of options). Since I am not engaged or married, I will use my cousin's ring-shopping expierence of what to do(and not do). Ill start with the DO-NOT since that's more imortant. Do not just meander into a jewelry store without any kind of prior research. The people who work in jewelry stores are trained specifically for people who dont know what they are doing(I worked at a huge jewelry store for about 4 years and have a keen eye for guys that have no clue about rings.) Study what kind of jewelry she wears all the time(if any). Is it silver or gold. If gold, is it yellow, white, or rose gold.(look online at stores like zales and debeers and such for differences between the different metals) Does she wear rings that stand up off of her finger(called a prong setting) or are they closer to her hand? Does she prefer diamonds or another stone(for instance i prefer sapphires). If all of this seems entirely too daunting, the easiest way to get out of having to make an actual decision yourself is to take her with you. Take her out to lunch(obviously somewhere that you cant drive through) and then go ring shopping. Then keep the thing captive till you can surprise her with a proposal. Tha ought to keep her on her toes... As an added bonus, its rather amusing to watch girls get dressed up every day b/c they want to look good in proposal pictures. Ive given up on this b/c my boyfriend knows how obsessed I am with the proposal pic, so I know he will do it while Im horseback riding or something.... Anyways. Good luck ring shopping!

Sorry girlie answering here. My husband had the sense to ask me what I would like, so I knew it was coming. But I have to wear this ring for the rest of my life, I wanted to love it, and it would have been a real shame for me if he had bought something I did not like. I would not have wanted to return it since he proposed with this ring. We flicked through a few catalogues and I picked out some rings which I liked and a few which I hated. It gave him an idea of what to get, then he went and bought one himself - diamond solitaire, can't go wrong there. My friend bought his wife a cubic zircona which he proposed with, and then took her shopping for a proper ring. She wears the zircon on a chain round her neck, and the real deal on her finger. Good idea I thought. Hope it all goes well when you find the right time / place / ring etc. :)