If you had to choose between ice(n=1.31), glass (n=1.52), or diamond(n=2.42) which would be the hardest lens to make? Which woukl be the easiest lens to make?? the one with the least radius of curvature would need the most work done on it because of the small value needed. On the other hand if the radius of curvature is large it would be relatively easy to make because of lesser wiork needed to make this lens. we're talking about making a thin symmetric convex lens here whoe focla length would be 10 cm in all cases. is this right? is this how this should be understood??