Crystals can be made at home by dissolving several common household chemicals, such as borax, Epsom salts or sugar, in hot water to form a solution. In some cases, crystals form rapidly as the solution cools. With other chemicals, crystals form over time as water evaporates from the solution.
Sugar crystals are a popular and safe type of crystal to grow at home because they require simple, common ingredients. To make sugar crystals, add 2 parts white granulated sugar to 1 part boiling or hot water, and stir until the sugar is completely dissolved. Pour the sugar solution into a jar or tall glass. Cover the container, and set it aside.
To form a starter, dip a cotton string in the solution, and allow it to dry on a non-stick surface, such as wax paper. Once the starter string has dried, measure it to the same length as the depth of the container, and then tie one end around a pencil or other similarly shaped implement.
Lower the string into the sugar solution until the pencil is resting across the top of the container. Make sure the string is hanging straight down in the middle of the container and not touching the sides. Cover the container loosely with plastic wrap to keep out dust or other foreign material.
Allow the solution to sit for several days. Crystals should be large and clearly developed by the end of one week. Because these crystals are made from sugar and water, they are safe to eat once they have cooled.