I bet they're repainted. You should be able to take a little acetone to the white and find yellow beneath it (at least on the metal emblems). The factory paint will be more resistant to the acetone so you won't take it off as easily as a repaint. Looking at them it's hard to tell, I have an emblem someone blacked out and the finish quality isn't that different from factory. If the person that repainted them did a decent job it would be hard to tell without checking to see if there was paint underneath.
Even the fender emblem on the top left of your picture looks like it might be repainted, the yellow and red don't appear to the right shades. But that's hard to tell from a picture. The one on the top right looks correct though.
All of mine are yellow, with exception of the blacked out one which definitely isn't factory.