  We investigate the effects of the reversal of the gravitational field onto a
sedimented and partially crystallised suspension of nearly-hard sphere
colloids. We analyse the structural changes that take place during the melting
of the crystalline regions and the reorganisation and assembly of the
sedimenting particles. Through a comparison with numerical simulation, we
access the single-particle kinetics and identify the key structural mechanism
in the competition between five-fold symmetric and cubic crystalline
structures. With the use of a coarse-grained, discrete model, we reproduce the
kinetic network of reactions underpinning crystallisation and highlight the
main microscopic transitions.
