Platinum, nearly twice as much as gold. Gold does, platinum does not. White gold is easier to clean, but platinum will always retain its color.
White gold can take on a yellowish cast over the years.
Both can be polished without fear of thinning or excessive wear as long as they are of high quality. Platinum is more durable, but gold is more scratch resistant. Platinum prongs are more secure and in no way will damage the stone. Also, platinum mounts will not add its own color to the stone whereas yellow gold can sometimes add a yellow tint to a colorless or near colorless diamond, making it appear to be a lower color grade. Platinum, because it is purer.