Abstract: A system is used to validate bottle caps, or top crowns, having particular reflectivity characteristics in plastic covering their undersides and in an alloy from which they are made. This permits the top crowns belonging in a particular promotion to be different, in these respects, from the rest of the top crowns on the market. Validation is carried out with the assistance of an identifying mechanism having an optical sensor and an inductive sensor in front of which the top crowns move while being carried by a conveyor belt or band when inserted in the identifying mechanism. The optical sensor works together with a generator of light having a given wavelength that is reflected by the underside of the cap or top. Thereafter, the light reaches the optical sensor. Signals generated by the optical and inductive sensors, upon the passage of the top crown, are duly processed and compared with the preset valid values in a suitable program.