These are natural crystals and may have natural cracks or irregularities. They have been polished so there is potential for polishing marks and scuffs, these have been reflected in the price but do not alter the crystals beauty or properties. Please see videos for more details
Clear quartz has the ability to enhance mental clarity, so it can help with emotional stability, and it is popular in meditation and restorative work.
It's also often used for manifestation and can help create more focus and clarity around a desire. It is a protective stone and can be used to amplify psychic abilities.