Hello everyone. I've been lurking here, doing the research. I've been working with Jonathan at GOG on an engagement diamond. I and my girlfriend have really enjoyed the process of getting educated. Thank you for all the super info here and for making me aware of GOG. Through Jonathan and Sarah at GOG, I learned that the big price jumps happen at the carat weights of 0.5, 0.7, 0.9 and then 1.0 and each quarter carat above that. Jonathan let me know that this is determined by market forces. Also that the price jumps are mitigated to some extent by the demand for the carat weights just under the jump points so that actual prices do not jump as dramatically as one would expect based strictly off the Rap sheet price jumps. I'm wondering if anyone has additional information about why the price jumps are at .7 and .9. This seems quirky. Are these numbers tied to some fact about diamond rough sizes or something specific? Or did someone just arbitrarily decide these would be the jump points? Why not at what would seem to be the more obvious choice of .75 carats? I could see people wanting to say that they had a 3/4 carat ring, but not that they had a .7 or a .9 carat ring. Why not .6 and .8? Just a point of curiosity for me. Thanks again for this fantastic website. -Nate