The metal marker from the Trinity Church graveyard at New York marks the grave of a Mason. It is the metal reproduction of what is perhaps the most recognizable emblem of the Freemasons, the square and two compasses. In this example the letter “G” appears in the middle of the emblem. Often the emblem is seen without the letter “G”.
Each component of the symbol represents a different Masonic orthodoxy, though, these are not hard and fast:
The compasses represent the boundaries of wisdom a person should have the strength to circumscribe and stay within.
The square symbolizes virtue in all actions, just as the expression “square deal” means treating people with fairness.
The letter “G” seems to have more than one meaning. It could possibly mean God, as in the creator of the universe; or Gimel, which is the word for the third letter of many Semitic languages. The number three is significant to many Masonic rituals and beliefs. Some also believe the “G” may represent geometry.