  With the observation of the gravitational wave event of August 17th 2017 the
multi-messenger astronomy era has definitely begun. With the opening of this
new panorama, it is necessary to have new instruments and a perfect
coordination of the existing observatories. Crystal Eye is a detector aimed at
the exploration of the electromagnetic counterpart of the gravitational waves.
Such events generated by neutron stars' mergers are associated with gamma-ray
bursts (GRB). At present, there are few instruments in orbit able to detect
photons in the energy range going from tens of keV up to few MeV. These
instruments belong to two different old observation concepts: the all sky
monitors (ASM) and the telescopes. The detector we propose is a crossover
technology, the Crystal Eye: a wide field of view observatory in the energy
range from 10 keV to 10 MeV with a pixelated structure. A pathfinder will be
launched with Space RIDER in 2022. We here present the preliminary results of
the characterization of the first pixel.
