I'm gonna take a wild guess here and presume you have the other essential cat lady accessories taken care of, namely the cat hair on your clothes and wild, manic glint in your eye.
These will just finish it off perfectly and make your friends worry about you.
They come as a set of 4 rings
The size of the hearts are 2cm on average (0.8 inches)
The rings themselves are stainless steel and can be easily adjusted to fit any size :)