Extensive large-scale global optimizations refined by ab initio calculations are used to propose (SiO2)N N=14-27 ground states. For N<23 clusters are columnar and show N-odd-N-even stability, energetically and electronically. At N=23 a columnar-to-disk structural transition occurs reminiscent of that observed for SiN. These transitions differ in nature but have the same basis, linking the nanostructural behavior of an element (Si) and its oxide (SiO2). Considering the impact of devices based on the nanoscale manipulation of Si/SiO2 the result is of potential technological importance.