Graphite Colors - Set of 6  Kuretake Gansai Tambi watercolors are a perfect addition to any desk or studio. Traditional Japanese watercolors are more opaque than Western transparent colors, making them simpler to use and a more direct medium for quick sketches. If you need more transparency for a particular project, just add more water and Gansai Tambi can also create lighter washes. These luminous solid watercolors are perfect for illustration and botanical sketching.