Note: I don't recommend the fitting of roller nuts or compensated nuts. Find out why here
*Stainless steel is now my default choice of material for full refrets. In addition to its hardness and wear resistance I believe this offers improved tone. Users report increased definition in chords and improved sustain, particularly of the high end harmonics.
Nickel silver fretwire is still available for partial refrets and vintage or historic instruments.
**Nut may require replacement. Bound fingerboards, lacquered maple fingerboards and unusual material will incur additional costs
*** Guitars equipped with locking nuts may be subject to a surcharge if work is required to correct the nut height; it is essential that this is correct if a set up is to to be right, so it is not negotiable. Also, guitars in a heavy state of disrepair may require additional work to unseize rusted screws etc. These may incur additional costs at a pro-rata labour rate.
All prices quoted are exclusive of strings
Bone is a very traditional material for guitar nuts, although many early instruments favoured ivory. With this material being in limited supply and mostly illegal, bone is the next best substitute. Bone is very hard and it's naturally greasy nature makes it a good choice for tuning stability, but it needs to be correctly cut. See here for more information about this
There are now many synthetic substitutes available for bone. Fender "bone" nuts are actually a phenolic resin called Cyclovac.
Micarta, favoured by Martin as a saddle material and S&P, Norman, Art of Luthierie and many smaller makers is a composite of resin and various materials. It's a pretty lousy material, and rather soft, easy to handle but impossible to polish.
Graphtek "graphite" nuts and Tusq are mostly plastic and some manufacturers use ABS (PRS) and even polystyrene.
Plastics are a poor choice of material but the Phenolics are some of the better plastics, being quite hard and durable. Bakelite is an example of a Phenolic resin and is often found on some cheaper guitars.
The best synthetic material is Corian, an artificial marble invented by DuPont as a material for kitchen worktops, i tend to keep a block of the stuff hanging around for vegetarians and vegans. I don't know why, but that always seems to get a laugh; why should a vegetarian or vegan notobject to having a piece of dead animal on their guitar?
The traditional metal nut is brass, but I favour phosphor bronze as a better alternative. It has better corrosion resistance and restitution characteristics. Many grades are self lubricating, having been designed as bearing alloys
Stainless steel is much harder, and offeres the ultimate in wear and corrosion resistance but is very hard to work with, but you can expect a Stainless nut to outlast the rest of the guitar.