A method and system for detecting a diamond signature

A method for identifying the presence of partly liberated diamonds in a material stream, said method comprising the steps of:

• illuminating a material with a multi-wavelength beam comprising at least one monochromatic SWIR laser beam, and at least one IR scatter-/anti-scatter laser beam,
• capturing a portion of said at least one monochromatic SWIR laser beam after said monochromatic SWIR laser beam has been reflected and/or scattered by the material,
• producing a SWIR signal based on the captured portion of said at least one monochromatic SWIR laser beam,
• capturing a first portion of said at least one IR scatter-/anti-scatter laser beam after said at least one IR scatter-/anti-scatter laser beam has been scattered and optionally reflected by the material,
• separating and thereafter capturing a reflected portion of said at least one IR scatter-/anti-scatter laser beam after said at least one IR scatter-/anti-scatter laser beam has been reflected by the material from a portion of said at least one IR scatter-/anti-scatter laser beam after said at least one IR scatter-/anti-scatter laser beam has been scattered by the material,
• producing an IR scatter signal based on said captured first portion of said at least one IR scatter-/anti-scatter laser beam,
• producing an IR reflection signal based on said captured reflected portion of said at least one IR scatter-/anti-scatter laser beam,
• classifying the material as comprising diamond based on the presence of a diamond signature in the combination of the SWIR signal, the IR reflection signal and the IR scatter signal.