How do I sterilise Pearl earrings?

A rubbing alcohol bath ought to do it.

Alcohol as @Nullo said is the way to go, I usually put earrings in a little cup of alcohol and let them sit for abt an hr that way if anything is stuck on there soaking will get it off.

Pearls are to be handled differently than stones. Research this further before immersing them in any type of solvent.

Here’s a page that gives instructions on pearl care—there are many on the web, and they all saynotto use solvents or harsh chemicals—https://thepearldoctor.com/Pearl_Care.html

Can’t you dip the earring fitting in alcohol without the alcohol touching the pearl? Only the fitting touches your skin.

I would just clean with a gentle soap the entire earing and then after drying clean the backs with alcohol. Most viruses and bacterias die off on dry surfaces, so there is little risk of acquiring some sort of dangerous blood born disease to begin with. Plus, ear earing holes are healed over and there is no open skin.