This is a question I got a lot from my customers.
Believe it or not, crystals hold onto the energy they take in from you and from their environment. It’s good practice to purify their vibration on a regular basis
There are few ways and you can googled it, of course. But since the questions I got are for the jewelry that I made for my customers, the best way to cleanse their energy is by placing them under direct full moon for about an hour or two. When the moon is full, she is at her brightest, making it the most powerful time to release what is no longer serving you.
Place them on the ground or any natural surface like wooden table, etc.
Sun have a very strong charging energy but many crystals like Amethyst, Aquamarine, Citrine, Fluorite, Rose Quartz, and Smoky Quartz for example will fade in direct sunlight. Therefore, if you wish… after the full moon cleansing, you can charge your crystals and gemstones during sunrise for an hour or so.
Personally, I like to close the cleansing by charging my crystal with healing and positive intentions once they are all back inside. You can charge them as a group or one by one.
Hope this helps!