Crystals only work when activated.
But first they must be cleaned and purified and this regularly so that it continues to act with maximum effectiveness.

How to clean your crystal or stone:

If this is not said to weld in water, do not crumble and are not formed in layers, hold it under running water for a few minutes then deposit the water sun or in the light of the moon for 6 hours to re-weldenergize, you can add coarse salt. For the most fragile you can immerse it in rice or clean it with incense smoke or bran.

How to activate your stone or crystal:

Hold it in the palm of your hand, focus on it, and say aloud, “I dedicate this crystal to the greatest good of all that will come into contact with it.” If you want to program the crystal to achieve a specific action called it with clarity and conviction out loud.

How to preserve its crystal and stone:

Despite the hardness of some stones and crystals they remain fragile and can be damaged.
They should be kept in a small cloth bag when not in use.
Know that exposure to sunlight can discolour them.

How to choose your crystal or stone:

If you seek to cure a particular evil you may choose it for the definition of its virtues. Otherwise you can also choose it by chance.
Have confidence in your intuition, look for the one who will talk to you when you look at the images either in real or on the internet. There will probably be several possibilities.
You can also test it, take the one you like in your hands and hold the palm closed for a few moments. If you feel tingling in your hands, it’s the right one.
Remember that the most beautiful and the greatest is not necessarily the most powerful.
Small and irregular can be extremely effective.
You can also use a pendulum or radiesthesia.