There are various ways to cleanse your crystals. If you're referring to only how to clean your jewelry, just use a soft microfiber cloth / towel. If absolutely necessary, you can wash it with mild soap, warm water and soft toothbrush but ONLY if the jewelry is made of metal such as stainless steel, copper, bronze, brass or precious metals like Sterling Silver / Fine Silver and Gold.
NOTE: Make sure not to do so with Tarnish Resistant metal as you might scrub off the tarnish-resistant coating. Just use a dry or slightly damp soft microfiber cloth / towel for this range of accessories.
Now, if you're asking about how to cleanser / recharge your crystals, there are a few choices. Pick one that's convenient for you but don't overthink it. Just let your intuition guide you...
Here are my 8 favorite ways to do so:
1. Singing bowl - the meditative vibration is a form of sound healing and can recalibrate the energy of the stones you have. If it's large enough to place inside the bowl and create the vibration that is best, but you can always just use the singing bowl near the crystal. Just like how you get to enjoy the healing vibrations even if you yourself are not sitting in the bowl ;)
2. Crystal chips, Geodes or Crystal plates - Just place your crystal on top of these when you remove them to shower or go to sleep every night.
3. Under running water - every wonder why you feel refreshed and reenergized after enjoying the beauty of a waterfall? When you sit under one (obviously a tiny one that will not crush you!), the soothing flow of water will work it's magic and emit negative ions that are healing, also like how it feels after it rains. Placing the crystals under running tap water for a minute will work here if it's more convenient for you. Then just towel dry them and you're done.
4. Under direct sunlight - 1 hour is sufficient. 20 mins should also suffice, just like humans need that much of time in the sun to absorb vitamin D :)
5. Under full moonlight - do it overnight. It's also very romantic.
6. Bury in the earth - just as long as the earth is alive (if worms live in it, it's perfect!) it will do the trick! Harness the power of earth itself, even for us humans, it's good to walk or stand barefoot on earth every now and then to reconnect back to mother nature. Remember to dig the crystals out after a day, or you might forget about them.
7. Sage / Palo Santo sticks - burning these and chanting, 'may the healing power of this Sage / Palo Santo cleanse and reenergize these crystals'. There's something very spiritual about doing this, and when you do so, you also cleanse your space...
8. Salt - I don't really recommend this because there are some crystals that will become dull afterwards so unless you already know which ones are able to withstand this, there are many other options to choose from...
How often should you do these? Once a week or every alternate week. It's also recommended to do so if someone else touches your crystals, you have visitors in your space, if you have had a bad day, or even a quarrel. In any case, when you do so, it will bring back some form of positive energy to harness from.