1.51 ct. Leucite - The Gem Trader Rare Gems

1.51 ct. Leucite

  • Color:  Faint Yellow
  • Clarity:  Slightly Included
  • Origin:  Near Ostia, Italy
  • Cut:  Cushion Mixed
  • Treatments:  None
  • Measurements:  8.6 x 7.1 mm

An extremely unique gem species with fine gems in excess of 1 carat being particularly rare.  At first glance, you may think this is just simply another rare colorless gem material, but the attraction of Leucite resides in a very unique optical phenomenon.  Firstly, it is one of the very few gems having an isometric crystal form (like garnet or diamond) that actually has a birefringence - the result of a complex process whereby it forms isometrically at high temps and changes to a tetragonal structure as it cools without changing the outward crystal structure.
 Secondly, as a consequence of its lamellar structure and resulting diffraction, Leucite can have an opalescent quality that will produce a color flash.  Hence, you have what appears to be an opal-like 'play-of-color'.  There is no other gem material that comes close to imitating this effect.  This lovely example is a fine and large cushion and has an excellent color flash.  Just touch the gem with a little direct lighting and the unexpected flash becomes apparent.  The intensity of the spectral flash varies considerably from stone to stone and is quite strong in this example.  

$165 / carat - $249 total