A method for identifying the presence of partly liberated diamonds in a material stream. The method can include illuminating a material with a multi-wavelength beam including at least one monochromatic SWIR laser beam, and at least one IR scatter-/anti-scatter laser beam, capturing a portion of the at least one monochromatic SWIR laser beam after the monochromatic SWIR laser beam has been reflected and/or scattered by the material, producing a SWIR signal based on the captured portion of the at least one monochromatic SWIR laser beam, and capturing a first portion of the at least one IR scatter-/anti-scatter laser beam after the at least one IR scatter-/anti-scatter laser beam has been scattered and optionally reflected by the material.