bottom half turned upside down, with Onchion additionally swapping places with Topazion, the lists become extremely similar; there are only four differences: Onchion (literally onyx) has become sardonyx (red onyx) Anthrax has become chalcedon (literally meaning chalcedony, of which the red variety is the most common). Anthrax literally means coal, presumably meaning the red colour of burning coal. Ligurios has become chrysoprason. Scholars suspect that ligurios was a pale yellowish mineral, and although chrysoprase now refers to a specific gemstone which is generally apple-green in colour, in earlier times it referred to gems of a yellowish leek-green, such as peridot; chrysoprase literally means golden leek. Achates (agate) has been replaced by yacinthos (jacinth). According to classical rabbinical literature, the specific agate was of a sky-blue colour, and though jacinth now refers to a red-tinted clear gem, this was not the case at the time the Book of Revelation was written, and at that time jacinth appears to have referred to a bluish gem; Pliny describes jacinth as a dull and blueish amethyst, while Solinus describes it as a clear blue tinted gem – the modern sapphire. Pattern Whether there is any pattern to the choice of gemstones depends on their identity. Taking the majority view of scholars in regard to the identity of the gems, and including the implication from the Book of Revelation that the onyx at the end of the fourth row was a sardonyx'', there are four colours – red, green, yellow, and blue – each represented by a clear gem (red – carbuncle, green – heliodor, yellow – chrysolite, blue – amethyst), an opaque gem (red – carnelian/red jasper, green – green jasper, yellow – yellow jasper/yellow serpentine, blue – lapis lazuli), and a striped gem (red – sardonyx, green – malachite, yellow – pale golden agate, blue – sky-blue agate). The four colours of red, green, yellow, and blue, are the first four colours (apart from black and white) distinguished by languages, and are distinguished in all cultures with at least six colour distinctions (the other two being black and white). These colours roughly correspond to the sensitivities of the retinal ganglion cells. (The retinal ganglia process colour by positioning it within a blue to yellow range, and separately positioning it within a red to green range.) See also Ephod Priestly golden head plate Priestly robe (Judaism) Priestly sash Priestly tunic Priestly turban Priestly undergarments