Even though these results were obtained with CZ material, diamond appearance can be modeled with this software (see Figures 7 and 8) by using the appropriate refractive index and the absorbtion spectrum. It is advisable to use several controlled lighting conditions when designing and optimizing new cuts because of diamond's variability in appearance under different lighting conditions. Diamond proportions that have an inconsistent appearance under different types of lighting can be avoided. A good diamond cut should have an attractive appearance under all lighting conditions. One can use computer models of several common illuminations to predict stones appearance before stones are cut. Magna Colorscope light on Magna Colorscope light off Ring 6 cm Ring 17 cm Office Jewelry store   Figure 7. Colored diamond models under various illuminating conditions. Stones size 7 mm.