The electromagnetic calorimeter of the CMS experiment is now entering the c
onstruction phase. Consequently the crystal production will soon start. The
preproduction phase which started in august 1998, is foreseen to allow for
further optimisation of the final crystal production scheme. A general ove
rview about the quality and characteristics of the first large batch of the
preproduction crystals will be given and the results will be discussed wit
h respect to the final production requirements needed for high resolution c
alorimetry for CMS.