The other, other magic note

Some readers may have realised that the symmetry associated with the D note* must have a counterpart. That note is G# or Ab, which is the place where the musical alphabet wraps around. It has a special relationship to D which is a flat 5 (or sharp 4), which places it exactly half way between an octave span from one D to another. Here's an image of the piano keyboard showing the symmetry around G#/Ab:


* see the original 'magic note' post

Here are a couple of images showing the physical relationship between D and G#/Ab on the fretboard (note that the nut and 1st fret are not shown):





That relationship should make it easier to learn where all the G#/Ab notes are in relationship to D as it is almost always either 1 string and fret higher or 1 string and fret lower. The only catch is when going between strings 2 and 3 (the G and B strings) where the guitar tuning makes the span 2 frets rather than one: