Blue

Egyptian Blue: one of the earliest if not the first known synthetic pigment, a bright blue, was made by the Egyptians with a mixture of copper, sand and natron.

♀ – The symbol for Venus, the goddess of love and beauty and for her planet is thought to be a stylized mirror.
Copper was used to make early mirrors, and is thus associated with beauty and Venus.
It was also used in alchemy as the symbol for copper.

Many languages do not have a separate term for blue and green.

For instance, the ancient Egyptian word wedjat means blue and green. It is also the name for the well-known Eye of the Moon, which later became the Eye of Horus and the Eye of Ra.