The end that tips down is heavy. I paint my nylon/glass props with a little green flourescent testors model paint on the light end to add a bit of weight. The paint adds visibility to the propeller's outer arc and it's much easier to balance a nylon/fiberglass prop by adding weight than trying to sand it down.

Once the propeller is going 12,000 rpm, you can't tell only one tip is painted. I can also tell at a glance if a propeller is balanced or not by whether or not I painted one tip.