SAPPHIRE  ,1 a

blue transparent variety of corundum, or native alumina, much valued as a gem-stone . It is essentially the same mineral as ruby, from which it differs chiefly in colour . The colour of the normal sapphire varies from the palest blue to deep indigo, the most esteemed tint being that of the blue cornflower . Many of the crystals are parti-coloured, the blue being distributed in patches in a colourless or yellow stone; but by skilful cutting, the deep-coloured portion may be caused to impart colour to the entire gem . As the sapphire crystallizes in the hexagonal system it is dichroic, but in pale stones this character may not be well marked . In a deep-coloured stone the colour may be resolved, by the dichroscope, into an ultramarine 1 Indirectly from Gr. o&orq5uupos, but there seems no doubt that this term, like the Hebrew sapir of the Old Testament, was formerly applied to what is now called lapis lazuli; the modern sapphire was probably known as u&xwOos (hyacinthus) . colour . It is a silicate, containing aluminium, magnesium and iron, brought originally from Greenland, and since found in a rock from the Vizagapatam district in India . (F . W .