Well, she never noticed it on her own. I decided to try to draw attention to it so I went up and looked at the 4 nutcrackers on the mantle and said "hmmm, this one has a crooked foot." She said "yeah, it's been like that." So I fixed the foot and put it back on the mantle. Nothing.
Maybe she already saw the diamond and was just messing with me? So I said, "Hon, do you notice anything weird about any of the nutcrackers?" She said "What did you do?" assuming I had drawn male genitals on one of them. I said "look closer at them." "No the ones on the other side." Took her a few more seconds and she FINALLY noticed the diamond. Pure surprise! Mission Accomplished!
I told her it had been hanging there since Wednesday and I couldn't stand it anymore. She is super happy and cried saying she didn't get me anything, it cost too much, it's too huge, etc... But after 36 years of marriage, I know she loves it.
Now I can't wait until Xmas morning when she finds the earrings in her stocking. Not even gonna try to hide them.