Shenzhen hong zheng technology limited have own turquoise mine which is a professional handmade manufacture 100 natural gemstone jewellery which can supply thousands different kinds of natural gemstones. Aquamarine is one of the few naturally blue untreated gemstones although some darker stones may be heated and it has excellent hardness and durability. The most common blue stone is a sapphire however the deep blue color can also be found in other gemstones such as kyanite lapis lazuli and zircon.