These are the two recommended to me previously here and elsewhere:
the diamond zone and peter suchy. The second seems a little pricey, but I know very little, so don't go by me.
also, they are not ebay but if you are looking for old diamonds there is always old world diamonds or jewels by erica grace. They are just websites though. Or you can sporadically check the preloved forum and Diamond bistro/ loupetroop.
there is one on there currently that was graded a RB but looks like an old cut, and very well priced.
Thanks. That is stunning but somewhat over my budget. Does look like a great price. Doubt that I am a quick enough shopper to snag it if I chose to blow my budget anyway.