Congratulations to Tom (PhD student) and Jack (prevous Masters student) who's work has been published in ChemComm. This article describes the synthesis of a new Cu31-oxo cluster, the largest cu-oxo cluster known with only O-donor ligands. This structure has a condensed Cu+O core making it similar to a CuO nanoparticle. A size-colour relationship is observed in Cu-oxo clusters showing how they smoothly transform from small Cu coordination complexes (blue) into larger clusters (green/yellow) before finally reaching nanoparticles (brown).