Can't get diamonds to look real in rendering

Can anyone tell me what settings need to be changed to make Diamonds look really good when I Render (I using polished white gold with a white ground plate) , I turned on the skylights, I watched the webinar on that showed how to make the 4 different white ground plates. I have Brazil 2.0   Do I need to edit the diamond material?  I got it to look good once when using The Metting Room as my Enviroment, BUT it made the white gold and the diamond turn yellowish.  THANKS IF ANYONE CAN HELP