THE PHYSICAL AND CHEMICAL-PROPERTIES OF SYNTHETIC AND NATURAL JADEITE FOR JEWELRY

Jadeite was synthesized from its glass of stoichiometric composition NaAlSi2O6, and a colouring agent Cr2O3 (0.3-0.6 wt%) was added to achieve the emerald colour. The conditions employed were a pressure range of 3.0-5.0 GPa and a temperature range of 1150-1750 degrees C, for periods of 1-480 min. The physical and chemical properties of synthetic jadeite, such as microstructure, unit cell parameters, melting point, thermal stability, hardness, density and refractive index, etc., were compared with those of natural jadeite. The optimum crystallizing conditions for the synthesis of jadeite for jewellery were above 4.5 GPa, 1450 degrees C and 60 min. The synthetic jadeite was emerald in colour, translucent, 12 mm diameter and 6 mm thick.