it's advisable to cleanse them. Crystals have their own unique vibration and can be affected by the energies of the environment.
Ideally cleansing is to clear energies that do not belong to it prior to using, or wearing them. You will need to do this again from time to time to make sure, to maintain the energies of the crystal.
Cleansing your crystals can be like a meditation. You may wish to see it as a practice of spending time 'going inside', connecting with your intuition and spending some time being very conscious.
Choose a method that you would be comfortable with, or explore all of them and work out for yourself, which method ( or maybe 2) is sustainable for you.
Cleansing with water or intent, is one of the most common methods of cleansing your crystals. Do not that there are some crystals that are not suitable to be soaked in water. They are Selenite, Angelite, Halite, Turquoise, Kunzite, Kyanite. You may wish to use an crystal cleansing spray, which does contain herbs, and alcohol, to simply spray and wipe!
Personally, I don't recommend soaking in salt water. Although if you feel that you need to use salt, you may wish to use a bed of rock salt and bury your crystal in it.
If you have been attuned to Reiki you can hold the crystal in your hand and draw the symbols over it with your dominant hand and intend for the energies to start to cleanse and charge your crystal. If the crystal is much bigger, you may wish to use both hands.
Smoke from incense is an ancient way of cleansing, not just for crystals. We use herbs such as white sage, or a palo santo incense stick. We would light a tea light candle, and hold the white sage cluster over it so it ignites and creates smoke. We use a ceramic bowl with a handle, to house the smoking leaves, and hold the crystals above this bowl, allowing the smoke to bathe the crystals. We prefer to use white sage clusters because you can control how much you wish to use, and you don't have to 'stub it out' and leave the half burnt leaves in your store room. With the remaining ashes, you can just throw it away.
For Palo Santo Sticks, I would use the same method of using the tea light candle, hold a stick of palo santo ( if there is another piece, please keep it dry) at a 45 degree angle over the flame, to light the wood. You don't have to 'stub' out the stick because it will extinguish by itself. Be sure to also use a ceramic container with a handle, because the container you use may get hot and you will use it to contain the burning ashes.
There are other resins that you can use to do this, but you will need to light a tablet of charcoal and when its lit, put the resin on top of the lit charcoal. You can view the resins we carry here.
You may wish to use a singing bow, tuning fork or tingsha. Using the vibrations of the bowl, to cleanse the crystals. You can ring the bowl or tingsha for a minute with the crystals in front of you, or if you feel that you need to do this for longer, please follow your intuition.