A magnificent diamond ring, by J. Roca. photo: Christie's Images Ltd 2010 The ring composed of a cut-cornered rectangular diamond weighing 17.71 carats to the tapered baguette-cut diamond shoulders with plain hoop. Signed by J. Roca. Estimate $1,000,000...

Icy jadeite and diamond ring and pair of matching ear studs The ring centring on a highly translucent icy jadeite cabochon, within a twisted border set with brilliant-cut diamonds, to a double shank; and a pair of ear studs en suite; mounted in 18 karat...