Controlled crystallization of emerald from the fluxed melt

The problem of controlled crystallization of emerald single crystals from a fluxed melt, its colour characteristics and optic parameters are discussed . Properties of the as-grown single crystals are very much like those of na tural gems. Emeralds weighting as much as 150 ct grown on oriented seeds in dynamical regime feature small dichroism, uniform distribution of colour i n the volume to offer good jewelry characteristics. The (1 0 (1) over bar 0 ) and (1 1 (2) over bar 0) cuts of previously grown crystals is established to be the optimal seed. The technique has the advantage of maintaining the optimal concentration ratio of the solute near the crystallization front t hrough adequate stirring by a platinum crystal holder is rotated at a rate of 30 rounds per minute, and seed positioning. To examine emerald crystals quality we have performed a laser experiment and threshold measurements. La sing was achieved at absorbed pump energy threshold of less than 0.6 mJ. (C ) 1999 Elsevier Science B.V. All rights reserved.