These are my go to methods:
– Let them sit in sunlight and moonlight. Depending on the type moon (full, half, pisces, libra etc) you can even give particular intentions a boost.
– Bury them in salt.
– Wash them cool water.
– Bathe them in an herb infusion or tea. Bitter or sour to clean and cleanse (ex: lemon or pine). Sweet to bring intention (ex: lavender or clove). Hot to activate (ex: ginger or chili).
– Surround in smoke. Dried Herbs are most often used- like sage, palo santo, or rosemary. Prepare your herb bundles for your intentions, for example: burn sweet herbs like lavender for sweet intentions. Incense is a useful alternative. Be careful.
– Store next to medium to large-sized selenite; ask the selenite to keep your stones clear. Selenite is excellent as it is a self-clearing stone.
– Breathe on your crystals. Blowing a cool slow breath with your intentions after one of these or even just because activates your crystals and stones to you.