Sugar crystals are used to make rock candy. They are mainly created by dissolving sugar in boiling water and allowing it to form crystals. Food coloring can also be added to the mixture to create colored crystals.
To make sugar crystals, the first thing you should do is to boil water. While waiting for the water to boil, tie one end of a string to a pencil or a pen. Use cotton or wool strings. Avoid using a nylon string as sugar will not crystallize on this type of material. If you have no other material except a nylon string, tie a paper clip at the other end of the nylon string. The clip is where the crystals would grow.
Once the water is boiling, add a teaspoon of sugar and stir slowly. Keep adding sugar and stirring until you notice it accumulating at the bottom. This means that saturation point has been reached and the sugar is no longer dissolving.
If you prefer to make colored sugar crystals, add in a few drops of food coloring. Afterwards, pour the mixture in a clear glass jar. Do not let solid bits of sugar get inside the jar.
Put the pencil over the mouth of the jar, with the string hanging inside. Place a paper towel on top of the jar. Place the jar in an area in your home where it will remain undisturbed.
After a few days, check your jar. You will notice crystals have already formed on the string. Let the crystals form until they stop or until they have reached your preferred size. Carefully take the string out of the jar and dry the crystals.