The new technique of ion structural chromatography is applied to carbon clusters. The results indicate that C5+ and C6+ are purely linear but C7+, C8+, C9+ and C1O+ have both linear and monocyclic ring structures. From C11+ to C20+ only monocyclic ring structures are observed. At C21+, a new family of planar ring structures appears. The first 3 dimensional structure occurs at C29+ and the first fullerene at C30+. Isomer structure is verified by the comparison of experimental mobilities with those derived from theory for the various structures. For C20+ only the monocyclic ring is observed experimentally but electronic structure calculations suggest more compact structures might be lower in energy. The results are discussed in terms of possible growth mechanisms for C60.