Yellow Sapphire, the Gem of Jupiter

Yellow sapphire is the yellow variety of corundum, aluminium oxide, coloured by traces of iron; at hardness 9 it shares the extreme durability of all sapphire. Much commercial yellow sapphire is heat-treated to deepen or clarify the colour, and some pale material is irradiated, so disclosure matters in the trade. Its single most important traditional role is in jyotisha, where under the name pukhraj it is the gem of Jupiter, Guru or Brihaspati, and one of the nine navaratna stones; it is among the most commonly prescribed astrological gems in India, worn to strengthen Jupiter's benefic influence on wisdom, prosperity and marriage. That is a living, documented tradition with a substantial prescriptive literature. Yellow sapphire is also one of the September birthstones as a colour variant of sapphire. Its broader metaphysical associations largely restate the jyotisha character of Jupiter in modern terms.