The Ritter Royal Flora Aurum because it is called, has a body carved from a piece, a rare solid from maple while the nut is carved out of a giant ivory 10,000 years. Fingerboard is decorated with floral inlay pattern made of 24 carat gold. There's even a black diamond set in platinum decoration of each leaf. Even the bridge, tuner buttons and knobs are cast in gold. The buttons on the bass continues to lavish decorations-they both topped with brilliant-cut diamonds (3.3 carats total).
Source : http://most-expensive.net/bass-guitar