1.94 ct. Leucite
Color: Faint Yellow
Clarity: Eye Clean to Slightly Included
Origin: Near Ostia, Italy
Cut: Oval Brilliant
Treatments: None
Measurements: 9.7 x 7.6 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. And then there is stone - surely one of the best we have seen and likely one of the finest of the species. The size is excellent, the stone is nearly eye clean (totally clean stones tend to lack in spectral flash) and the stone is well cut. However, what is truly stunning is the flash of color in this gem - just touch the gem with a little direct lighting and the unexpected flash becomes apparent. You can rotate the stone endlessly to find new angles to enjoy these surprising colors. The intensity of the spectral flash varies considerably from stone to stone and we see colors in this stone we have never seen in Leucite before. A remarkable stone.