Book Matched Material
Book-matching is the process by which a plank of wood is sawn down the middle and opened up like a book, so that the resulting two pieces are near mirror images of each other. The grain pattern of a 'book-matched' soundboard should reflect this symmetry.
This is done only on ornate objects, such as furniture, violins, guitars or the interior of super luxury cars such as Rolls Royce cars. Bookmatching is usually done with veneer (produced in one of several ways), but can also be done in the solid. The two adjoining surfaces are produced from the same piece of wood, so that they have (almost) exactly the same figure, but mirrored. The final effect varies with the figure of the wood chosen and can range from extremely subtle so that it appears to be a single piece of wood, to dramatic effects with very wavy grain showcased in high end guitars.