Diamond Color Grading Set, Available in one-carat size, a set of 10 stones (color range from D-M). Comes with an attractive case. The unique grading display/container is made of color grading-approved white acrylic & is equipped with a built-in grading tray. All stones are laser-inscribed with Color Letters for easy identification and handling. These CZ stones are made with Nano Technology in Japan with the highest standards of production. These stones have a 10-year warranty for the color.