If only I knew enough to make a seperate thread worthwhile Rand.
I am just a student myself...
Much ivory coloring is just surface patina or induced through, age & dirt & sweat, tea, smoke ,chicory were often used to colour items or the Chinese favorite for turning it yellow is nose sweat!
Hard heavy white ivory of good quality came from Guinea, cameroons ,Gabon & the Congo. It is what many antique dealers refer to as Indian as it has the same percieved look and qualities of jungle dwelling Elephants of India & Burma. It is the favorite of Oriental carvers as it will polish like glass.
Soft ivory is sometimes veined with darker streaks & used to mainly come from Senegal,Ethiopia, Egypt, Sudan & Kenya. It was popular for Billiard balls & piano keys as it was easy to work.
ill have a look through my libary & notes & see what else I can find on the subject.
Spiral