Platinum vs. White Gold Ring Mount: Identification & Testing

Question
One last thing on this ring mount.  I couldn't get a straight answer from Zales.  I originally had a platinum mount, this new mount does not look like a platinum mount to me (but what do I know...).  Can you tell by looking at that picture which it is ... platinum or white gold?  Thanks

Answer
NO Im sorry honey I cant tell from the pic, it has to be tested or a jeweler will know the platinum head is heavier in weight because of density in the metal, in addition a white gold head will eventually show a little yellow with time, platinum will dull in white color but will always stay white as its a noble metal with no alloys.
les