What is the item in the picture?

Maximino, I don’t need jewellery to tell everyone I’m a grumpy old man!

I remember mood rings from when I was a teenager in the mid 70's, those and Pet Rocks were a "must have" for some folks.

If you have cold hands your ring will tell you that you are sad or in a bad mood all the time .

I want to buy this mood ring to test my moody behavior