Ross-Simons - .90ct t. w. London Blue Topaz Cross Pendant Necklace. 18". Expressive .90 ct. t. w. marquise London blue topaz gems adorn this beautiful cross pendant necklace, set in polished sterling silver and suspended from a cable chain. For a person of faith, it would make a special signature December birthstone piece or gift for a religious milestone. Springring clasp, London blue topaz cross pendant necklace. Blue Topaz birthstones are the perfect gift for December birthdays. Topaz Birthstone, Beautiful Cross, Necklace Blue, Cross Jewelry, December Birthstone, Cross Pendant Necklace, London Blue Topaz, London Blue, Cable Chain