Correlations between admixtures and color centers created upon irradiation of natural beryl crystals

Colorless samples of natural beryl which are of little value were irradiated by a neutron flux from a reactor, gamma rays from a shutdown reactor, and gamma rays from a 60Co source to impart gem color to them. As a result of selection of irradiation conditions for samples of pale aquamarines and emeralds, different sample colors were obtained. It was shown using neutron activation and x-ray radiometric methods that the acquired colors and hues of beryl crystals depend on the presence and content of Ca, Sc, Ti, V, Fe, and Co admixtures. It was established from optical absorption, reflection, and luminescence spectra that the induced color centers are related to replacement of cation site of structure by impurities.