Large Vivid London Blue Topaz & Diamond 9k Gold Ring Size I. It is an amazing ring, the large blue topaz gemstone really looks amazing and is finished off with genuine diamond accents to the top of the four claws. It is fully hallmarked for 9ct gold with "9k", the anchor for Birmingham(quite hard to read) and the makers mark "TGGC". It weighs 4.3 grams. Size I. Excellent condition.