The individual silica nanoparticles (glass beads, basically) are clear, but when packed together in certain configurations can give rise to flashes of color. This is due to Bragg diffraction off ...

Glass making originated in the Near East around 2000 BCE in the form of beads, seals and inlays ... and exporters of this time were the Phoenicians who had a great supply of silica rich sands. Glass ...