Gb major 13th chord
Gbmaj13 chord for piano with keyboard diagram.
Explanation: The G flat major thirteenth is a six-note chord (the 11th, B in the case of Gbmaj13, is normally excluded). For practical reasons the chord is normally played with omitted notes and/or inverted. It is often abbreviated as Gbmaj13 (not to be confused with Gb13).
Theory: The Gb major thirteenth chord is constructed by extending the major eleventh chord with a major thirteenth note.
Notes: Gb - Bb - Db - F - Ab - Eb