Cerium Fluoride, a new, dense, fast and radiation hard scintillator, is at present the favored candidate for high-resolution calorimetry at future colliders. This crystal has been extensively studied – in particular by the Crystal Clear Collaboration – and the conditions for production of large, high-quality crystals are now being optimized in seven firms all over the world. Recently the collaboration has received several CeF3 crystals, up to 17cm long, from three companies. A small assembly of such crystals with silicon photodiode readout was exposed to high energy electrons and muons in the H2-beam of the SPS at CERN. The results of these tests with longitudinally segmented towers are presented and discussed, in particular in terms of light yield and energy resolution.