My timing is amazing.....for you anyway. I just came from a very reputable dealer as I was viewing my first Lazare. After being dazzled by the rock, the conversation turned to the setting. He gave me what I believed was some solid advice. He showed me some unpolsihed white gold and platinum side-by-side. The white gold was definitely whiter. He also claimed that the platinum would look more "grey" over time, and the white gold would stay whiter.
He had a nice selection of both metals, and I was prepared to spend more $$ on the platinum. Other interesting advice he issued was about the crown. He claims that a good crown starts as one piece of metal and is "single struck," stay away from forged. He also said that quality crowns are tumbled in a slurry to actually polish the inner prongs. I could clearly see what he was talking about.
I'm still learning about diamonds, but I was blessed with amazinly good vision (20/12).....even at 36!
Hope this helps. Now if you could just help me buy the right diamond for the perfect girl!
Good Luck
Kev