I bought and installed a couple ivory shotgun beads a few years ago. The elephant ivory bead is already starting to yellow but the hippo ivory bead remains as white as snow.

I got them off a guy on eBay. When I went back to his website to buy a couple more he was shut down. I figured the guv put the clamps on him.

I think if faced with replacing a missing ivory bead on a front sight today I would fab one out of an ivory substitute of which there's a couple available, or make a solid gold one out of my old wedding band. Personally I like a gold bead instead of ivory for all around visibility anyway.

"You can lead a man to logic, but you cannot make him think." Joe Harz
"Always certain, often right." Keith McCafferty