I experimented with several ratios of glue, food colouring and water and believe the magic ratio to be: 1 tsp of glue : 3 drops of food colouring : 1.5 tsp of water. But you might want to try different ratios and see what you results you prefer. Obviously the more food colouring the darker the jar will be. In order to make a turquoise shade you will need two drops of blue and 1 drop of green.