The signature, Square and Compass with a ‘G” in middle of ensign. Square - is a geometric symbol. Compass - represents geometry and building. “G” the letter G stands for God. It is the most identifiable symbol of Freemasonary.
Masonic Blue, the colour blue is a sacred colour. Different hues of blue have been used by Royalty and Masonic Blue is synonymous with Freemasonry over several centuries.