Orange (colour) with green, of yellow with violet ... trying to make the colours intense and not a harmony of grey". In another letter he wrote simply, "there is no orange without blue." Van Gogh, Pierre-Auguste Renoir and many other impressionist and post-impressionist painters frequently placed orange against azure or cobalt blue, to make both colours appear brighter. The actual complement of orange is azure – a colour that is one quarter of the way between blue and green on the colour spectrum. The actual complementary colour of true blue is yellow. Orange pigments are largely in the ochre or cadmium families,
Orange (colour) it contains arsenic and is highly toxic. It was also used as a fly poison and to poison arrows. Because of its yellow-orange colour, it was also a favourite with alchemists searching for a way to make gold, in both China and the West. Before the late 15th century, the colour orange existed in Europe, but without the name; it was simply called yellow-red. Portuguese merchants brought the first orange trees to Europe from Asia in the late 15th and early 16th century, along with the Sanskrit "naranga", which gradually became part of several European languages: "naranja" in Spanish, "laranja"