Where did my necklace go?

All right, where is it?  I know I left it on my bedstand when I went to bed.  I had it there, I know I did.  I was so careful because it is so precious to me.  My Granddaughter heart necklace with my mother's ring.  Now where did that thing go?  I have checked the bedstand; I have checked under the bed; I have checked the floor; where in the world---I should have known!