Using real elephant ivory can be problematic, I would avoid. White bone is good and is attractive. However, I have used a white front sight and did not like it. The white can vanish in bright sunlight or against a light target. Some disagree and like them. I prefer a black post. The black will contrast and stand out against almost any target, even in low light. When the light is gone and you can't see anything, that is the time to go home.