It's a beautiful stone anyway. Nearly everyone pays way more. You might have been able to pay a bit less, but not a truly large amount less.
Most folks prefer to be treated fairly and pay a fair profit to a retail seller.
Anyone else's opinion is hardly worthy to consider unless they know you very well on a close personal basis. Hello, I know who the cutter was for that diamond. It's a beautiful stone anyway. Dear J, I would not worry at all about the girdle unless it is in an exposed setting with the thin bit in a vunerable position, and even then thin is not extremely thin. Also any dealer who says what margin another dealer should charge has no right to do so in my opinion, especially with out the knowledge of level of services provided.