The never-ending resetting project

I was going to wait until I had something to show for the last year of staring bug eyed at hundreds of vintage rings and settings, but I have come to a place where I am not sure what I am hearing is correct.
A little background... Last December, my grandmothers ring mysteriously disappeared (I think I might have left it on our front porch where it could have been taken, but who knows.) Anyway, luckily we had insurance. Unluckily, replacing an heirloom is impossible. Luckily, I found old cut diamonds. Luckily, I found one on Ebay for a great price. There were other dealers who offered more than me, but I promised not to recut the diamond. Yay me! Oh, and I have pics and the original owners' "story"...really cool to me that it will be added to by our family now.
Okay, when I got the ring, I took it to a friend's jeweler to look at settings only to have him tell me it was trash and that I was screwed. Frantically, took it to an appraiser (well known here in Dallas) who I was quoted one price for the appraisal, but after was charged $70 extra. He did confirm the diamond was a keeper though. Thankfully, since then, I have been able to use pricescope for quite a bit of help and I have had two really awesome ladies (who know who they are on here) help me stumble thru my learning process.
I am using another jeweler locally. I would definitely rather use a known estate/antique dealer, but I just think its better to go local if I am going custom (um...one of my "lessons.")

Here's a pic of the diamond in the old setting below.



My first question is about white gold versus platinum. I have read the threads on here about the differences, and I am impartial to platinum. The patina doesn't bother me. Ease of scratch...no problem. But, the current jeweler seems to have an all out repulsion to platinum. Stating that, when polished, a lot of platinum is lost (versus white gold, which he swears is minimal). He also says that platinum is virtually a waste of money because white gold is just as good. He tends to do a lot of modern jewelry, so I am assuming the shiny white gold is just something he prefers??
1. Is what he is saying correct?
2. Is there a better metal for millegrained (sp?) pieces? Will the millegrain hold better against polishes in a platinum or white gold piece? Or no difference?

Sorry for the long post. Hopefully the finished product will be more exciting. I will post the CADs when I get them. I tend to suffer analysis paralysis when it comes to this...