The symbol on a Masonic ring is a combination of a Masonic square (symbolizing earthly perfection) and a compass (symbolizing heavenly perfection). Sometimes the letter G is incorporated into the center of the design. The ends of the square point up to show human beings' aspirations toward God; the points of the compass point down to represent heavenly qualities coming down to earth from God. When pressed into wax to validate an authentic Masonic document, original Masonic rings left a raised image of the symbol.

...

Choose a finger on which to wear your Masonic signet ring. Married men typically wear their Masonic ring on the right hand. The little finger, as opposed to the ring finger, is a popular choice.

...

Buy a Masonic ring that fits the finger you’ve chosen.

...

Set the ring on your finger so that the legs of the compass face away from you. The original Masonic signet rings had to face this direction to ensure that when the wearer pressed the ring (with his fist) into warm wax, the legs of the compass pointed down on the resulting wax seal.