How should I clean the chewelry?

You can:

Scrub them with mild soap and water, or
Put them the dishwasher (just don't turn on the drying cycle), or
Boil them for a few minutes. Just be sure to wait a few hours before using again, so that they can cool to the core not just to the touch.

If boiling, the cords should be removed first (so that only the pendants are boiled).