A collection of four gem set rings

A collection of four gem set rings, comprising: a sapphire and diamond cluster ring, the oval-shaped sapphire within two concentric ballerina surrounds of baguette-shaped and round brilliant-cut diamonds, in white gold, size N; Mouawad, a diamond ring of interlocking link design, set with round brilliant-cut diamonds, in white gold, stamped 750 and Mouawad, size M; a diamond ring of openwork design set with a row of round brilliant-cut diamonds with a pavé-set terminal, in white gold, stamped 750, size O; and a diamond ring of openwork design set with round brilliant-cut diamonds, in white gold, size approx N 1/2