Jargoon is the older English spelling of jargon, the historical trade name for pale yellow, near-colourless or smoky brown zircon. The two spellings refer to the same material and have been used interchangeably in nineteenth and early twentieth-century English-language gemmological literature, with jargoon the more common form in British usage of that period and jargon the more common form in continental European mineralogy.

Definition

Jargoon refers to zircon, the mineral species ZrSiO4, in its pale yellow, near-colourless or smoky-yellow varietal appearance. The historical use distinguished the jargoon name from hyacinth, which referred to red and brown zircon, and from cinnamon stone or other separately named varieties.

Properties

The varietal shares the optical and physical properties of zircon as a species, with a refractive index of approximately 1.92 to 1.98, a hardness of 6 to 7.5 on the Mohs scale, and high dispersion of around 0.039 producing strong fire under direct light. Jargoon material is most often of high-type or intermediate-type zircon with sharp double refraction.

Sources

The principal historical source for the jargoon material described in nineteenth-century English literature was Sri Lanka, then known as Ceylon, with secondary sources in Burma, Cambodia and Madagascar. Sri Lankan stones have a long history of trade through the Dutch and later British colonial gem markets and were the most familiar source for the eighteenth and nineteenth-century European jargoon trade.

Use in Jewellery

Jargoon was used in eighteenth and nineteenth-century European jewellery as a less expensive alternative to white diamond, particularly in cluster mountings and pendants where its strong fire could be displayed to advantage. Antique pieces sometimes contain jargoon stones that have been historically mistaken for old-cut diamond at first viewing.

Modern Usage

Modern trade and gemmological practice has largely abandoned both jargoon and jargon in favour of the species name zircon, with descriptive qualifiers indicating colour and treatment. The historic spellings nevertheless persist in older catalogue descriptions, in the works of nineteenth-century gemmologists such as Edwin Streeter, and in the conservative practice of some antique-jewellery dealers and auction-house specialists.