While the above description of colors used in Icons is the general concept used in Byzantine iconography there are variations. First, many older Icons were written in different parts of the world where some pigments were not available. There are many classical Icons where green has been substituted for blue because blue pigments were not available. Many older icons have been retouched over the years and variation in colors occur on the same Icon due to differences in pigments. Over the years many Iconographers have deviated from the traditional styles and incorporated new colors into Icons.