Crystals you can make, they sell kits at toy stores that allow you to grow different color crystals of all shapes and sizes. But there is a difference between a crystal and a gem. A crystal is manly a solidified chemical structure or compound (iodine makes a nice purple crystal). Gems are made of crystallized minerals and metals (anything from diamond to quartz)and take countless centuries to make and craft in the earth including tremendous temperature and pressure that cant be repeated in a lab. Sorry but Gems cant be human made yet. Also crystals are fragile and can shatter with picked up while gems generally wont.