LOCUS (mathematics)  'a curve or other figure formed by all the points satisfying a particular equation of the relation between coordinates, or by a point, line, or surface moving according to mathematically defined conditions'

Two small symmetrical shapes hang on a sterling silver curb chain and sit beautifully together. 

The circle measures 10mm and the semi circle measures 15mm. 

Materials- The shapes are a mix of brass and sterling silver (the circle is sterling silver) 

Sterling silver curb chain measures either 46cm/18 inches.

By- Custom Made