Homemade rock candy is commonly formed by allowing a solution of sugar and water to crystallize onto a string or some other surface suitable for crystal nucleation. Heating the water before adding the sugar allows more sugar to dissolve and thus produces larger crystals. Crystals form after several days. Food coloring is often added to the mixture to produce colored candy.
Candied sugar has its origins in India and Persia. Arabic writers in the first half of the 9th century described the production of candy sugar. Crystals were grown as a result of cooling supersaturated sugar solutions. In order to accelerate crystallization, confectioners later learnt to immerse small twigs in the solution for the crystals to grow on. The sugar solution was colored with cochineal and indigo and scented with ambergris or flower essence.
Rock candy is a different product from British , also called seaside rock, which more closely resembles a candy cane.
Rock candy is used in Chinese cuisine. It is used to sweeten ''tong sui'' and chrysanthemum tea, as well as .
Rock candy is called 'Mishri' in Hindi and is widely used in India with aniseed as a mouth freshener, especially after meals. In telugu, it is known as "patika-bellam". One can find these two being offered along with the check/bill, at most restaurants in India. Rock candy is called 'Kalkandu' in and is commonly used in Tamil Cuisine especially in Jaffna .
Rock candy is also used in Mexico to make sugar skulls on the celebration of the Day of the Dead. Children make the rock candy in the shapes of skulls by special strings and then decorate them with icing and jewels. These are eaten after the festivities.