Hello, my grandfather used to work with ivory many years ago and he
taught me many things about ivory.  The first thing is ivory will
discolour without light and, in the case of piano keys, sweat from
the fingers or nicotine and any other liquid on the finger tips will
discolour the ivory after a while.

As for the initial colour, the African ivory is the best quality and
is slightly ivory in colour.  Indian ivory is very white and usually of
a more coarse grain.  There is also a forest elephant whose tusks are
quite straight; the ivory from these can be very discoloured from
continually pushing through undergrowth.

A tusk is hollow for so much of its length and then becomes solid.
High quality items were made from the solid end, and the nearer the
nerve centre the better, where the grain could be invisible.

Ivory was cut by handsaw and by powered saws, also veneers were cut by
first turning part of the tusk true, then using a special lathe with a
long horizontal saw.  (That's how sheets of ivory were made to veneer
those large boxes we see sometimes.)

Last of all, tusks where often used as money in days gone by.

I hope this is of interest to you.

Terry Newberry