Lots of ways to cleanse a crystal, but in essence there shouldn't even be reason for that. Depends where you buy it.
I mostly only buy (very) high vibrational crystals from a shop of which the owners are very pure and whose Soul path it is to do that work: find these crystals, buy them for a good price so they can also offer them in their shop for very reasonable prices, making it possible for everyone to obtain good quality & high vibrational crystals.
They never get crystals in that are lower vibrational, they'd just skip those and often are allowed to hand-select the best ones a miner/ seller has in stock. They're usually allowed to do that as they buy so much.
In any case, that's how the crystals I buy are clean, pure, very high vibrational.
At home I have so many by now (almost 400 high vibrational ones) that they've formed an energyfield and help keep each other -and me- at a high level and clean.
Meaning I rarely have to cleanse / recharge any crystal. Ifever I put crystals in the full moon's light it's an extra, to give them the opportunity to download new/other high energies & codes.
The only ones I do regularly cleanse & recharge are the shungite tumbles as I use 1 to tape on my neck for pain and the other one to make crystal water.
These I put on a larger wand of selenite after a couple of days of using them.
Selenite is my preferred way of cleansing & recharging as it's easy and fast.
But... when I was living in another house with lots of nasty energies, a difficult relationship etc. I did have to cleanse regularly. I then put them in water for 12-24 hrs (beware that not all crystals can be put in water though!!!).
These days I sometimes check a few crystals, but they never need cleansing / charging. They pretty much take care of themselves & each other
