Former description from Gamblin (applying to old formulation with genuine Alizarin Crimson): “Alizarin Crimson: Cool, slightly bluish red with smoky glaze. 19th century “lake” color made by the fusing a dye on to a substrate. Only Alizarin Crimson is still commonly used by painters today.“ -Gamblin Oils. Updated statement for new formulation with PR177: “Alizarin Crimson is the most fugitive pigment we work with, meaning with time and exposure to sunlight the color will gradually diminish. Alizarin Crimson Permanent has the highest lightfastness rating whereas Alizarin Crimson has the lowest lightfastness rating.  We were the first colorhouse to develop an Alizarin Permanent. Robert Gamblin formulated our Artist Grade Alizarin Permanent over 20 years ago. His goal was to provide artists with a more stable color, true to the historic working properties of Alizarin Crimson. Our 1980 Alizarin Crimson Permanent is based on the same pigments and formula as our Artist Grade. Alizarin Crimson Permanent matches Alizarin Crimson in transparency very well. In masstone, it is somewhat lighter and cooler in value than Alizarin Crimson. Because it is formulated with modern pigments, it is more intense in tints and retains its chroma in mixtures more strongly than Alizarin Crimson.” -Gamblin Email Update