Patent ID: 7126351

Claim:
Method for qualifying gemstones by discerning gemstones from one another on the basis of their electrical conductivity, comprising: (i) placing at least a part of a gemstone ( 15 , 16 , 17 ) that is to be qualified in the electrical stray field of a capacitor; (ii) measuring the electrical capacitance of the capacitor; (iii) comparing the measured capacitance to a reference capacitance of this capacitor when a reference material ( 12 ) is placed in the electrical stray field, the reference material ( 12 ) having a dielectric constant which is smaller than 15 and larger than that of the gemstone ( 15 , 16 , 17 ) to be qualified, and (iv) qualifying the gemstone ( 15 , 16 , 17 ) as a gemstone with electrical conductivity when the capacitance of said capacitor, measured when said part of the gemstone ( 15 , 16 , 17 ) is in the stray electric field, is larger than said reference capacitance.