Sarin Colibri Diamond Colorimeter for Color Grading Polished Diamonds. Sarin’s Colibri is a state-of-the-art, user-friendly color grading product for polished diamonds. Its new technology uses hi-tech LEDs and software algorithms to not only calculate the color of the diamond, but to measure its fluorescence regardless of the diamond’s size and shape. Colibri can measure mounted stones, is fully portable and has a touch screen for ease of use. Results are easily readable on a bright display.