Black Buffalo Horn Guitar Nuts are softer than Bone, pearl or other materials.
In fact they are so soft that they can bend a little.
These are oversized so they can be sized and shaped by the luthier.
They can be polished to a high shine or just sanded to a 400 grit for a satin finish that will match nice with an ebony fretboard or bridge.
It is a good idea to round over the sharp edges of the string slots for wound strings to avoid a popping sound as the string tightened or looseden over the nut.
They will give a warmer tone than bone and other harder materials.