pigment

In art and crafts, a colouring-matter used in paint or dye. In the past, pigments were powders made by grinding various minerals, plants, and even animal or insect parts. The most expensive pigments were gold, vermilion (a red pigment made from sulphur and mercury), and ultramarine (a blue pigment made from the gemstone lapis lazuli). Modern pigments are made from chemicals and can be produced in more vibrant colours that resist fading. Paints can now be produced cheaply, making them less expensive to buy.

In early religious paintings the Virgin Mary nearly always appeared in blue robes because ultramarine was the most expensive paint, worth more than its weight in gold; its use, therefore, was confined to the most important subjects.