“Open pit extraction, referred to locally as “illam mining,” represents the most common and time-honored approach employed in Sri Lanka's interior gem fields, especially throughout south central areas. This technique requires vertical excavation through successive layers of surface material to access the illam, a productive gem-containing layer made up of decomposed gravels, clay, sand, and organic matter, typically situated several feet beneath ground level.”

“Riverbed mining represents a traditional approach employed across alluvial plains and riverine environments, especially when seasonal water reduction occurs. This methodology capitalizes on the natural accumulation of gemstones that have been conveyed and settled by water movement throughout extended historical periods.”