The deep blue pigment
made from the precious stone Lapis Lazuli was always prized above other blues, and was sought after by princes to adorn paintings as a status symbol. Attempts to make the color by simply grinding the stone proved unsuccessful as the coloring component of the stone needs careful processing. A by product of its manufacture was a light greyish blue pigment called Ultramarine Ashes which was actually the remains of the stone with the ultramarine removed.
Although chemically identical to the synthetic Ultramarine, genuine lapis pigment has a different crystalline structure when viewed under a microscope. This gives it a particularly beautiful appearance and there are still a small number of painters who use the genuine article. The pigment is still made in the hills of Afghanistan. The last time I checked the oil paint was selling for about $400 for a tiny 5ml tube.