The semi-precious stone jade traces its roots back to the Neolithic period, 3500 to 2000 BC, when it was used in Europe to make weapons. As jewelry, it was used by the Aztecs, Mayans and Olmecs. The Spanish called it 'piedras de yjada', meaning 'stone of side pain', believing that the Aztecs used it to treat kidney problems. The term yjada became 'Jade' in English. The two main colors are blue and green. Both colors of this gem are enchanting varieties of jade and often have soft, muted tones that mimic the serenity of sky and sea. Blue jade is associated with peace and inner harmony, promoting a sense of calm and serenity to reduce stress and anxiety.