Custom guns have to be evaluated as individual works of art. Some of the factors considered include skill of workmanship, extent of coverage, artistic appeal, and uniqueness. Factory engraving brings a premium over engraving of unknown origin. Sparse coverage brings less than full value.
A major determining factor on non-factory engraved guns is the reputation and skill of the engraver. As with other artists, the acknowledged masters of the form bring substantial premiums over unknown engravers. When dealing with an unknown engraver, the quality of the work determines value. Finest engraving is always done with hand tools-chisel and hammer. Crudely done engraving can actually lessen the value of a firearm.