This is a pendant associated with Freemasonry. About the letter G, Some say it’s as simple as standing for “God” and “Geometry”. Others believe it represents the word “Gnosis” , meaning the knowledge of spiritual mysteries, which is a big component of Masonry. And Like many religious entities, the Masonic Altar represents a place where communion can take place with God. It’s where the Holy Book(s) are stored, as well.