The rear is stamped 9ct, pin is 6cms high and overall weighs approx 0.7 grams. The pin itself is gold plated base metal.
This is a very nice piece of antique jewellery !! Set with a largish solid Matrix Opal measuring 18mm x 12mm, overall pin is 69mm high & weighs approx 3.3grams. The stem of the pin is stamped 9ct, meaning the complete setting is 9ct.