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G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
G01N21/84—Systems specially adapted for particular applications
G01N21/87—Investigating jewels
FR606373D1925-10-151925-10-15Procédé et appareil optique permettant de reconnaître les perles fines naturelles des perles fausses ou cultivéss
ExpiredFR606373A
(fr)