Turquoise, with its characteristic blue-green colour reminiscent of tropical seas, is the gemstone of December. It often shows an opaque texture with veins or spots of darker colour, which add depth and character to the stone. These veins can be natural, or they can be produced by mineral impregnations during the formation of the stone. It was considered sacred by many Native American tribes, who believed it had protective and healing powers; it was worn as an amulet to protect against dangers and diseases and to attract luck and prosperity. In the cultures of East Asia, turquoise was associated with wisdom and healing. Throughout history, many royal jewels and crowns have been adorned with turquoise. These jewels were often worn by members of royal families as a sign of status and prestige, as well as for their intrinsic beauty. King Frederick II of Prussia was an avid collector of exotic jewellery, including some pieces with turquoise. It is said that he was particularly attracted to the vibrant colour and beauty of turquoise, which he considered a gemstone of great aesthetic and symbolic value.”