A diamond cutter’s star gauge used to measure crown angles.

Diamond cutters use a star gauge to measure the crown angle from the table, which should –if the stone is accurately cut — coincide with the crown’s angle to the girdle plane. In cutting, consistent angles and depths, are a must, to end up with acceptable symmetry. This also leaves a table that is dead center and parallel to the girdle plane. Other methods of determining crown angles will be discussed shortly.