So, look at the side and back of this thing compared to the side and back of that hideous creature they are pushing on you.
www.briangavindiamonds.com/diamond-pendants/the-barbara-pendant-18k-white-gold-5352w18
You will notice that this one is super open, and that the diamond can get light from almost all around it. It's cast and or crafted from wire vs a stock die-struck mounting that is mass-produced which is what this one looks like because most likely they're just plucking something from a stock catalog and are looking for THE cheapest thing they can find to put your stone into. That just looks like some stock Stuller thing.
I inherited my grandmother's diamond studs and had planned to make a pendant for me and one for my daughter. I think they are about .5 carats each. The Barbara is EXACTLY what I've been thinking of! I also received a beautiful 20 inch scroll chain that I want to wear it on. As usual, Ame has the best suggestions!