Blue dyestuff is a type of dye that is used to color fabrics and other materials. The three most common blue dyestuffs are WOAD, ANIL, and INDIGO. WOAD is a plant-based dye made from the leaves of the Isatis tinctoria plant. ANIL is a synthetic dye derived from coal tar and petroleum. INDIGO is a natural dye made from the leaves of the Indigofera tinctoria plant. All three of these dyes are used to create a variety of shades of blue.