  We have studied magnetization of graphene nanocrystals obtained by sonic
exfoliation of graphite. No ferromagnetism is detected at any temperature down
to 2 K. Neither do we find strong paramagnetism expected due to the massive
amount of edge defects. Rather, graphene is strongly diamagnetic, similar to
graphite. Our nanocrystals exhibit only a weak paramagnetic contribution
noticeable below 50K. The measurements yield a single species of defects
responsible for the paramagnetism, with approximately one magnetic moment per
typical graphene crystallite.
