Rock Candy: 2 cups water, 1 cup white corn syrup, 3 1/2 cups sugar, 1/4 tsp cream of tartar. Then I added: 1/4 tsp vanilla extract, 3 drops of blue gel food coloring. Boil the mixture and stir it on the heat until it reached 300 degrees F (use a candy thermometer to measure the temp). Pour into a tray to cool. It will harden up in about an hour and then smash it to pieces.