Alcohol will kill most things and I highly recommend it for cleaning and getting your diamonds super sparkly. However, to really disinfect and be certain to kill any potential bad things, get a cup of really hot water and add just 2-3 drops of bleach. Soak for no more than 5 minutes. And rinse. You don't want too much bleach because it can pit your jewelry, but bleach will kill it all. I'm really paranoid about this because I once got a wart on my ear and it was traced back to just trying on a pair of earrings.
We learned at first aid that if we could figure out how to put bleach in the blood system without killing you, AIDS and many other diseases would be cured.