@Amit: from my small corner on retailing, I see all things: some stuff, even good stones, going at 10-15 back because it's not moving (e.g. some cushions or radiants), to people quoting 50+ over for indifferent quality rounds - whether they get it is a completely different thing. I suspect that there is so much variability in cost structures at the retail level ("premium street level shop" vs. "office in suburban location dealing via internet") that it adds even more "randomness" to the prices.   Multi-vendor listing engines like the Diamond Finder are actually a pretty good tool for getting an idea of retail prices - and they are free to use!   @Sandy: On the (non) investment - I'm looking forward to a more detailed "quoted" reply/conversation based on previous posts, but I'll let you catch your breath rather than adding more at this point. I have some pointers/observations that go largely in the direction that Amit has mentioned (and I also sketched in my previous posts): choose what is likely to remain desirable, rather than maximising current return (or minimising current loss, whichever).   On fluorescence - I think it's just a nice "added feature". It can give the diamond more of a "multiple personality" in different lighting conditions, even though in the majority of places it makes absolutely no difference. Many fluorescent diamonds are also phosphorescent, and it's fun to see which ones have it and in which colours it comes out (red and greenish blue by far the most common). The fact that fluorescent stones typically come with a discount is an added bonus.   In some cases, it really improves the look of the stone - rubies being a case in point: since most are strongly red fluorescent, they seem to have an inner light when exposed to the sun. I have a fancy deep orangy-yellow that has strong yellow fluoro; it is the closest thing to a "yellow ruby" that I can think of: in sunlight it just boils over with yellow light.    This is a mild case of haze due to blue fluorescence; the stone was noted as "Strong Blue" on the EGL report it came with. It is a 3.03 M/SI1h     A severe case would go almost completely white/fuzzy. You'd only see it on Strong/VS/XS lfuorescence. I have never seen haze happening in a colour other than blue, but there are accounts that for yellow it is also present, and it looks rather horrible...   The "yellow cancelling effect" is definitely there; I'd say it's far more noticeable on I-K or even I-M stones than on G-H. Here is an example in a J colour cushion (1.01 J/VS2/SB). First photo in no-UV environment (indirect sunlight, filtered through glass), then direct sunlight, filtered, then full sunlight with no filter:     The effect is the same on higher colour stones, except that of course there is no yellow to "compensate", so the stone shows a blue tinge of varying intensity whenever there is UV radiation present. Same three lighting situations as above for an F-colour pear (1.00 F/VS2/SB):     note that in neither of the two cases above transparency is affected; what you may see as "haze" is just the camera sensor getting total saturation (blow-off). It is rare to get haze - but it does happen.   The "negative" effect is that it causes a much stronger discount in D-G colour stones than it does in H-M ones, where in fact it may even lead to a slight premium. As I mentioned, I like the change in appearance, and I like blue as a colour, so the fact that the stone becomes blue-tinged is a plus for appearance in my book. Some people don't like it and want a consistent colourless appearance.