[misternoname]

Based on your spelling I assume you're in the UK. I'm in the States so I don't know if this will apply to you. I just purchased a ring (proposing over Thanksgiving Holiday). A good friend of mine is the VP of marketing for a national pawn shop. When they retain high end jewelry it's sent to their National Jewelry center in Vegas. He found me a G color Emerald cut 1.72 carat solitaire set in platinum. It's slightly included but you can't notice it with the naked eye. Paid $6000 tax, shipping and all. It appraised for $14000. Great deal. As far as I'm concerned most diamonds are "used" so the source is irrelevant. All I know is my fiancee to be will be sporting one hell of a rock and I didn't have to sell a kidney to get it!

[slowandsteady]

It's my understanding that cut is the most important. Also, if you go with a carat size that isn't round (.75, 1, etc.), you'll get the diamond for much less money and no one but a jeweler would be able to tell the difference.

You sound like you've done a bit of homework already. I think the next step would be to go look at some diamonds. The only way you'll get a sense of what's good is by going into jewelry stores and seeing for yourself and doing some good ol' comparison shopping.

I'd also recommend giving some serious thought to the ring setting. That's going to be holding the diamond after all. I'd get something that will hold the diamond the most securely and show it off the best. If it's within your price range, you may want to consider platinum. It's one of the strongest white metals, and it never loses it's whiteness. There's no point in getting a colorless diamond if the ring is just going to tarnish and reflect color in the diamond.

[allina]

It also depends on the cut of the diamond, as some cuts show inclusions more than others. For example a round diamond that is slightly flawed will look better than an emerald cut that is equally flawed.