The best Ebony used to come from the little island of Mauritius, off the East African coast. It is now protected and unavailable. Very fine ebony is still available from Gabon, Ceylon, and surprisingly, now from Cambodia.
I use only fossil ivory, mammoth, available through various sources in Alaska, the Canadian Yukon and Siberia. It must be carefully aged, treated and dried to be stable. I use this mostly for early bows, especially the ornate frogs of some French classical bows.