the finish is several coats of polyurethane
left pic: from the top around the rim clockwise is hard maple, red aromatic cedar, hard maple , a lamination of ash and 1/12" mahogany veneer, pau amerello, cocobolo, back to the pau amerello, a wedge of mahogany, honduras rosewood, and fir. The vertical at left is a lamination of hard maple thins and mahogany veneer. In the center from the top is purpleheart on the left and meranti on the right, then downwards is Honduras rosewood (sapwood on top, heartwood just below), a thin strip of ash, then tulipwood then a lamination of dark cocobolo surrounding veneer, the an ash thin, a mahogany thin, makore, cherry and red oak then down to the pau amerello.
the outer piece on the left is white pine (backed by hard maple) and in reality does not look yellow the way it does here but instead looks white. The outer piece on the right is hard maple and the facing piece is aromatic red cedar. The angled pieces at the left rear are pine and aromatic red cedar. The lines on the fir at the outer right show up much better here than in the upper left of the upper left pic.