Electron Microscope Mystery 6

It’s funny how when I posted Mystery 5 I thought that after August, things would calm down (at NSF and in life). Ha! No.

So I bring you another microscope mystery! The photo below is about half a millimeter across. What do you think it is?

Update: 1:10p

This is proving to be a tricky one, so here’s a 5mm-wide view…

Update: 1:18p

Nice job in the comments, Lori! The first image is a soldered portion of a ring – an engagement ring, in fact. A few years ago, my intern got engaged. She came into the lab and asked me to check if the diamond was real. I asked, “are you sure you want to know the answer?” She did. It was.