Product Code SKU7048. 9ct Yellow Gold Blue Topaz & Diamond Studs 5x7mm oval. Another stone type that has more than one colour Topaz can be found in blues, greens yellows, reds. The most common colour used in Australian jewellery is blue which looks good in either Sterling Silver, yellow or white gold.Topaz is one of the Birthstones for December. Beautifully presented in a gift box.