Alexandrite is an important material which finds applications in many spheres of science and engineering. It is present in nature as a mineral called chrysoberyl . But as its occurrence is limited and impure, this mineral has been produced synthetically to meet various requirements. This paper describes a sol-gel method of preparation of this mineral based on citrate gel processing and identifies the advantage of this method over the conventional macroscopic method. The gel formed by this process is pyrolysed at various temperatures and the powders obtained are characterised by XRD, SEM and particle size analysis. The diffraction characteristics of the samples sintered at different temperatures up to the melting point of the mineral so formed are examined and discussed with respect to the phase diagram of BeO-Al 2 O 3 system. It is found that at 1000°C alexandrite phase is obtained and it changes only after further heating up to the melting point, 1800°C.