That is Honduras Palisander burl. Actually, the finest piece of Palisander burl I have ever seen. I had to order that piece, at any price. The grain and color of the raw piece of wood was so exceptional, that I just knew it would turn into a work of art regardless of how bad I messed up the shaping process.
And then I got lucky and found a piece of buffalo horn that, when used the wrong way around, against the "grain" of the horn, would give the lovely pommel that can be seen on this knife.