silver-tone 18K white gold/18K yellow gold emerald-cut green emerald gemstone yellow diamonds three stone design prong setting 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. Includes an IGI Diamond Report. This certification from the International Gemological Institute assesses diamonds' cut, colour, clarity and carat weight according to strict international standards.