Winsor & Newton Cotman Water Colours are a range of water colours that are made to our normal high quality standards but costs are kept to an economical level by replacing some of the more costly pigments with less expensive alternatives. Each colour has good transparency, excellent tinting strength and good working properties. Winsor Violet (Dioxazine) is a vivid mid-shade purple pigment. When undiluted, it can be used as a deep black. It is a transparent coal tar pigment and was introduced into the Winsor & Newton range in the 1960s.