In this study, we found that the polymorphism and sintering behavior of silica can be affected by the size of starting particles. The formation of the stable tridymite phase, which is metastable unless a flux or mineralizer is present, is achieved with sintering of very fine silica particles of about 10 nm without the presence of a flux or mineralizer. Cristobalite phase is obtained as an intermediate as the amorphous phase transforms into the stable tridymite phase.