This is an 18k 750 yellow gold pendant by Hans Stern and (S in square cartouche) hallmark is on bail. This pendant is set with a pink Rhodochrosite gemstone that is translucent in clarity making is rare as it is normally opaque and sometimes called the "bacon stone". The gemstone is approximately a 16x12 mm oval cabochon cut with visible inclusions seen close up and minor wear to top of gemstone under very close inspections. The pendant is surrounded by 25 diamonds at approximately 1 mm in size. I estimate diamonds at .12-.15 points. The bail is very sturdy and wide for a generous size chain. The bail is an enhancer style so can attached to pearls though I suggest having the clip tightened a bit for security. The pendant is a 1 1/8 inch long and just over 1/2 inch wide. The Pendant is 5.8 in weight. Get collector item by a desirable designer.