Yes, I hope it's trustworthy because it's NASDAQ listed. And any diamond sold without the GIA might as well be made of glass.
Lot cheaper than any of the Chows. For HK$70k, 1.01 carat, VS1, E, Excellent cut inc 18k white gold ring.
Setting in HK, doable but a PITA plus additional risk that the stone you gave them is not the stone you get back (only half serious on this point), plus Blue Nile will give you good value rings in 18k white gold - quite frankly the girls will notice the stone more than the ring but suggest the 4 prong cathedral type.
Can't help with the split - I paid upfront on the visa but good idea to tell your card issuer you are going to make the purchase first.
Good luck!! Welcome to the suckers club!