In heraldry, an escutcheon is a shield that forms the main or focal element in an achievement of arms. The word can be used in two related senses. In the first sense, an escutcheon is the shield upon which a coat of arms is displayed. In the second sense, an escutcheon can itself be a charge within a coat of arms.

The lozenge in heraldry is a diamond-shaped rhombus charge, usually somewhat narrower than it is tall. It is to be distinguished in modern heraldry from the fusil, which is like the lozenge but narrower, though the distinction has not always been as fine and is not always observed even today. A mascle is a voided lozenge—that is, a lozenge with a lozenge-shaped hole in the middle—and the rarer rustre is a lozenge containing a circular hole in the centre. A lozenge throughout has "four corners touching the border of the escutcheon". A field covered in a pattern of lozenges is described as lozengy; similar fields of mascles are masculy, and fusils, fusily. In civic heraldry, a lozenge sable is often used in coal-mining communities to represent a lump of coal.