Glossary term
Illam
The Sri Lankan term for gem-bearing gravel.
Illam is the local Sinhala term for the buried layer of gem-bearing gravel worked by Sri Lankan miners. It consists of water-worn pebbles, sand and clay in which dense, resistant minerals have concentrated, typically resting on or near bedrock. Miners reach the illam through pits or shafts and wash it to recover gem rough.