I'm reading a piece that includes diamond-shaped whole notes at times. This signifies harmonics, if I understand correctly. What would I do, for example, if the music shows "Sul G" and then a diamond-shaped C above the staff? Do I play a harmonic at the C position (which I think produces a G) or do I hunt around for where the actual C pitch occurs as a harmonic on the G string? How about a diamond-shaped A on the top line that says Sul D? An E in staff that says Sul A? What pitches are they after? Thanks!