The February 2012 discovery of high-quality blue sapphires at Thammannawa near Kataragama in southeastern
Sri Lanka has intensified gem mining and exploration in the surrounding area and all over the
country. The deposit is hosted by the Kataragama klippe, and corundum mineralization is associated
with pegmatitic intrusions and surrounding micaceous layers. Well-formed crystals from this primary
deposit display flat faces and sharp edges with an unusually vitreous luster. The sapphires possess good
transparency and a pure blue color that is characteristic of corundum from this deposit. Several kilograms
of rough material have been produced so far, with some crystals larger than 200 g. Faceted blue sapphires
of fine color and weighing more than 20 ct have been cut.