Regarding this picture:First of all, Sierra could win it, not assuming that she doesn't. But, there is no necklace here.
*Sheldor placed the pics in order and this picture precedes the IC.
*Her hair is covering her bathing suit straps, it's not really a blurred area, imho.
*She is holding the same letters from home tube that the rest of them are holding
*She has her wallet that she probably got from tree mail tucked in her bathing suit top....you can see it in the pic above, and you can see it here, as she sits next to Shirin after the RC:
And, you can see her with the billfold here as well, and you can see Rodney holding his too....
So, while Sierra may win the second vote, (I doubt it), there is no definitive proof from vidcaps...imho