ACOUSTIC EXPO 2013: Tommy Emmanuel and Chet Atkins are surely the best known players who use harp harmonics. This technique allows you to create sweet-sounding, cascading melodic lines by mixing harmonics with regular picked notes.
The chiming sound of the harmonics, coupled with the sharp, cutting tone of ringing open strings, produces a rich, lush tone quite unlike the sound you get from fretting and picking every note.
The easiest 'natural harmonics' are played by lightly touching a string over the 5th, 7th, 12th frets. 'Artificial harmonics' are created by fretting a note and generating the harmonic, usually, 12 frets higher with your pick hand.