One of the most popular coloured gemstones for jewellery is the stunning blue Sapphire. Blue Sapphires are simply beautiful and one of our Favourite types of gems at Steven Stone. This is not only for their striking deep royal blue colour, but for their beautiful meaning as the gem of truth. The stone is made up of a variety of the mineral corundum, which is an aluminium oxide. One or our most popular Sapphire sellers is this oval shaped Sapphire and diamond engagement ring. Featuring two round brilliant cut diamonds set next to the deep blue Sapphire the ring is the perfect design.