A set of opaque watercolors and a cup of water: With these, children and adults can create imaginative artworks. Opaque colors are also known as watercolors because they provide good coverage and can be blended with water. Opaque watercolor sets come in various sizes and color assortments. The color tablets, with a diameter of 44 or 55 mm, can also be purchased individually. This way, you can expand your creative range or replenish the watercolor set when a color runs out.