You know, Pcarfan, if you don't know from watches, never mind dealers, there's a very good chance you should no more be looking online for thousand dollar+ Diamond watches than someone who has no clue about cameras should be searching on 'Pro SLR Take My Money' on Ebay.
If you have to trust someone, there's little substitute for 'In Person.'
*peeking at links.*
I suggest keeping some things simpler, too: I notice some of those Geneve ones are very formal, which usually takes a whole lifestyle and wardrobe to go with.
I suggest, if you want to make this venture worthwhile, enlist *spies.* Preferably, from among your lady-friend's friends.