gold-tone 18kt yellow gold vermeil polished finish tennis chain prong-set brilliant-cut laboratory-grown white diamonds totalling 52.2ct prong-set oval-cut laboratory-grown turquoise cabochon-cut laboratory-grown amethyst totalling 38.1ct clasp fastening Normal everyday use and external agents may reduce the lustre of gemstones and gold surfaces. To maintain, use specific, non-abrasive products specially meant for cleaning jewellery.