I used Photoshop and Illustrator to create the charts below. The purpose was to show the subtle differences in color and nacre of pearls. There was no source image for the pearls. I drew the pearls in Illustrator. To achieve the subtle differences in color and a sense of depth, I added many layers with different colors on top of each other. Then I adjusted the opacity of each layer. Finally I painted them in Photoshop using the airbrush tool.