We use special glue that is very strong in all weather conditions, i.e., car wash, storms etc. Crystals are not easy to fall off. Cell Phone Covers - with regular wear and tear i.e., (dropping the phone out of hand) it is possible for crystals to become loose. BUT no worries! You can send it back to us and we will replace the crystals that have fallen off. Same for our other items as well. Very rarely do the crystals fall but if for any reason crystals become loose just send us the item back and we will fix it for FREE all you have to pay are shipping charges.