His Jewel is the Square, which is a stonemason's tool to ascertain true and correct angles of the cut and smoothed stone...thus his Jewel symbolizes virtue.
The Worshipful Master of a Masonic Lodge is the highest ranking of all Lodge Officers. This position is similar to a President of any other organization. The Master of a Masonic Lodge is an elected officer of the Lodge.
The Worshipful Master is responsible for all business and activities within his lodge during his year as Master. He is ultimately responsible for every other lodge officer and their duties, every lodge committee, ritual and degree work, Masonic education, social functions, fundraisers, District and Grand Lodge liaison, and Trestle Board communications, etc.
Freemasons call the Master, "Worshipful Master", they do not, as some people may erroneously believe, actually worship him. "Worshipful" is an Old English honorary title which shows respect for his position.