Zircon crystalizes in the form of grains, tetrahedral and triangular dodecahedral crystals, and as short square prismatic crystals, often exhibiting the double pyramid structure. The mineral is also found with curved faces and edges. The colour range includes red, brown, green, yellow, orange, grey to blue, and white to colourless. Zircon, although known since ancient times, was first reported in 1783 by A.G. Werner and was named from the Arabic word "zargun" meaning "gold colour", referring to the colour of the specimen of first analysis.
Chemical Composition: ZrSiO4
"The Zircon includes Jacinth, or Hyacinth, and Jargoons, which, though differing in colour, are actually the same material species. As a rule amongst modern dealers in Precious Stones the White Zircon is known as the Jargoon, which is often found flawless and so bright as to closely resemble the diamond, being in fact often offered for sale as the diamond in Indian Bazaars.
Jacinths, or Hyacinths, are Zircons of deep orange or rich bright red colour, the Jacinth name being of Arabic origin, and the Hyacinth Greek, because it resembled the Hyacinth flowers which Apollo caused to spring from the blood of his favourite Hyacinthus whom he accidentally killed with a quoit. The remaining varieties of this stone, which are found in varying shades of yellow, grey, brown, and green, ranging from bright lively colours to dull cloudy shades, are described generally as Zircons, although very bright, clear, slightly coloured stones are described as pink or yellow Jargoons, according to the tint their colour may take. The best specimens come from India, Ceylon, Bohemia, France, and from Australia. Bœtius de Boot recommends the Oriental Jacinth, "that comes from Calicut and Cambray," as a specific for promoting sleep; Marbodus says it makes its wearer attractive and agreeable, which Barrett in his "Natural Magic" confirms, adding that if set in gold and worn on the finger it is a desirable jewel as a solace for a restless brain. Camillus Leonardus, writing in 1750, says the Jacinth will strengthen weak hearts, dispel imaginary suspicions, allay jealousy, secure travellers from injuries and thieves, and protect them from pestilence, plague, and contagious epidemics.
It was well known to the Ancients, and is considered to be the Lyncurion of Theophrastus. The popularity of this stone in India is as great as ever, and at the present time it is worn as an antidote against poison, to attract riches, honour, and wisdom, and to drive away evil spirits.
The virtues attributed to it during the Middle Ages were that it attracted success, brought welcome to its wearer wherever he went, stimulated the appetite, and aided digestion, protected from fever, dropsy, jaundice, and noxious fancies, and restrained from excesses, its efficacy being greatly increased if set in gold. But neither the Garnet nor Zircon should be worn by those whose birthdays fall in the Taurus or Scorpio periods." -The Book of Talismans, Amulets and Zodiacal Gemsby William Thomas and Kate Pavitt 1922