I think the stone has enough color on it''s own that it doesen''t need any help from rose gold, so to speak. Also, it''s on the purplish side and since everything else is white, the overall look is cool - so a warm rose gold setting might not be a very good idea. Now, if you want it to be less purple and more pink, that''s another story.
I am having a terrible time with this decision! I love the idea of both setting the sapphire in RG and Plat
The rest of the ring will be in Platinum for sure, as the side diamonds are M color with strong Fluorescence(which I love) they will need the white metal to keep them from having any more warmth! I love the 'old' cut look the cushions have
WOW those stones are gonna make one heck of a beautiful ring! I agree that while I LOVE rose gold, to me it looks "warmer" and your sapphire looks "cooler". I''d go with platinum for that beauty!