METAL: 18k Gold. MEASUREMENTS: Necklace is 17.5" long, center "pendant" section is 5" long x 30mm wide. GEMSTONES: Black opals, Diamonds - approx. 0.40-0.45ctw. MARKED: k18. WEIGHT: 71.4 grams.Gemstones have not been graded for color and clarity ,and tested for clarity and color enhancement, unless stated otherwise.