Hi Amie, I'm not an expert by any means, but I don't think you would want to have a white gold ring by a platinum ring... As another option, you might want to see about getting a palladium ring. It's in the same family of metals as platinum, so it should have a lot of the same shine, look, and characteristics. It's also a true white metal, whereas white gold is a mix which will give it a yellowish tint, which may contrast being right next to your platinum e-ring. Another option would be to get a stone other than a diamond if that doesn't matter too much to you. There are white sapphires or of course cubic zirconia, either of which would look good I think.. You might try going into a store and putting your ring up against other types of metals (14k/18k white gold, etc) to see if you notice a difference and decide if it would bother you if there was one. Whatever you go with, I'm sure it'll be beautiful! Good luck!