You can see pics of my diamond cut 8mm Kashmir here:http://betterthandiamond.com/discussion/...gged#Post565526
There is links in that post to my previous smaller stone too (7mm). If you do a search there are some other great examples around!
In person it looks fantastic! Obviously, as with any stone, lighting will affect the sparkle (and sapphires do not have the same sparkle as moissanite or natural diamonds do) but I never think of my sapphire as "flat"! Sapphires are definitely more about the colour - coloured stones are a whole different ballgame and people go for them for colour rather than flash! That being said, mine gives off plenty of blue flashes of colour.
I have seen the Chatham sapphires in person (at my jewelers), and compared them to my own, and personally, I pick (and did pick!) my own. Heck, I pick it over most of the "natural" sapphires I have seen in store!
I believe BTD uses the hydrothermal method for their sapphires.
There is Alexandrite offered by BTD, which has a colour change, but no colour change sapphires. I also know there is such a thing as lab created colour change sapphire...but I will be honest and say I have never seen a very good one...(not to say they do not exist!).
As for a more rectangular cushion...they do now and then offer custom cuts, but I think they just finished such an offer. I guess you could contact them and see if they have anything on hand, but my understanding it is costly to offer custom cuts all the time.