top nut for electric guitar, unbleached bone, 43,3x5,7x3,5mm This nut is made from unbleached bone, a long-time favourite of many luthiers. The slightly self-lubricating properties of unbleached bone as opposed to the very white bleached bone are a good reason to use this nut material. When polished, the looks of unbleached bone are very elegant and will add class to your guitar.