41. They may have optical properties differing from other facets. 42. These variations change the physical and optical properties markedly. 43. As different minerals have different optical properties , most rock forming minerals can be easily identified. 44. Protective coloring : Using color for its optical properties can help de-emphasize or accentuate the figure. 45. By careful selection of substituents it is possible to optimize crystal structure and improve optical properties . 46. For this various auxiliary lenses are in use that range in optical properties and practical application. 47. As such it should have better optical properties . 48. This will enhance the electrical and optical properties . 49. The defect symmetry allows predicting many optical properties . 50. Wheat vitreousness is an optical property used by many countries to grade or quantify durum wheat.