Gold pendant with blue Topas, which is sanded with the baguette method, which highlights the beauty and depth of the gemstone. 18K Gold with a Diamond and Topaz. The North London Blue pendant is made in 18K gold set with this magnificent 0.90ct baguette-cut London Blue Topas as well as their RO signature diamond. Brill. 0.003ct tw.vs. The pendant measures 9 x 5 mm without the box. This pendant is also made in 18K white gold.