Update:
The seller has great customer service and has offered to replace the necklace.  I have to change my rating to 5 stars now, because I do love the necklace.  The only reason I gave it a low rating initially is because of the missing stone.

Original review:
I'm very disappointed to say that the diamond in the middle was missing from my necklace.  I really love the way this looks, so I'm highly disappointed that I had to return it.  Since it's a "fulfillment" by Amazon, I could only get a refund, not an exchange.