Australia 1913 6d Blue/Ultramarine Kangaroo 1st Watermark Used. This stamp is a piece of history from the early days of Australian postal service. The 6d ultramarine kangaroo stamp is a rare find and is highly sought after by collectors. The stamp features a kangaroo, the iconic symbol of Australia, and is part of the first watermark series. The stamp has been used and has some signs of wear, but it is still in good condition and is a valuable addition to any collection. It is a must-have for any serious collector of Australian stamps.