I am a white gold lover. The reason why platinum gets a lot of hipe is because it is stronger, but why would anyone need the strength unless it was for the prongs? And I think platinum has too much of a grayish look to it.
White gold starts off as yellow gold, and then they add zinc, and nickle or platinum to make it a white color. Then they always dip it in rhodium to give it a bright luster. After a while the luster wears off, but only you can tell close up. And if you wear your white gold rings everyday you'll need to have them redipped every 3 to 4 years.
To have your ring rhodium dipped it should be $30.00. If you get quoted more than that I can tell you places that do it for $30.00. You should get it back in 5 days.
And to have that ring set in platinum will cost you about $1200.00+ and it would be better to just buy another ring.
Yours is fine just the way it is though. Very nice stone. Beautiful.
HC, is the table flat on the top? From the picture it looks rose cut. That is a faceted cut without a flat table (on the top).