Green ghost, green hair crystal, yellow ghost, yellow hair crystal, avoid buying artificial crystal, artificial color crystal, insist on rock crystal, otherwise the crystal will not help you, but will be harmful.
It would be better to wear a pendant. It will be purified after buying it back. Only you can touch it after wearing it, and no one should touch it. If anyone touches it, it needs to be purified before wearing it.
Generally, it is purified once or twice a week, and it is best to purify it every day if possible, which can help the crystal replenish energy. There are many kinds of purification methods, one of which is the most common and convenient for me: first wash it with tap 15 to 20 minutes, and then take it to the sun for an hour. Of course, the longer the time, the better. If there is no sun, it is ok to blow the wind and avoid Tomb-Sweeping Day and Halloween. That water can be used for washing clothes, but it can't be used for drinking. There is also a good purification method: when it rains, hang the crystal out to get wet. It would be better if it is a thunderstorm, but you must pay attention to your own safety.
Well, good luck ~ ~ ~