1.58 ct. Italian Leucite
Color: Faint Yellow
Clarity: Slightly Included
Origin: Near Ostia, Italy
Cut: Pear Brilliant
Treatments: None
Measurements: 10 x 6.5 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 remarkably large for a fine quality Leucite and has a superb display of color. Some gems have almost no detectable colors, while others, like this one, light up by comparision. Just touch the gem with a little direct lighting and the unexpected flash becomes apparent. Impressive gem in a very impressive size.