Concentrates from the DMS plant are examined for diamonds in a separate laboratory area specifically designated for diamonds. The stones recovered at this stage are (for samples under 100 tonnes) greater than 0.85 mm in size as measured by a square aperture screen. They are verified, described and measured in the same manner as the diamonds recovered from the caustic fusion residues.
Technical staff observe also observe the residues from the caustic fusion circuit in a specific area of Stornoway's laboratory. After separation from the dust-like residues, each diamond is verified, morphologically described and precisely measured before storage.