text: "Nanoscale" is usually understood to be the range from 1 to 100 nm because the novel properties that differentiate particles from the bulk material typically develop at that range of sizes.
  For some properties, like transparency or turbidity, ultrafiltration, stable dispersion, etc., substantial changes characteristic of nanoparticles are observed for particles as large as 500 nm. Therefore, the term is sometimes extended to that size range.