Size of dispersed phase particles in colloid?
Its between $1-1000nm$ as stated on wikipedia in a paragraph name IUPAC definition.



  Colloid: Short synonym for colloidal system.
  Note: Quotation from refs.[3][4]
  Colloidal: State of subdivision such that the molecules or polymolecular particles dispersed in a medium have at least one dimension between approximately 1 nm and 1 μm, or that in a system discontinuities are found at distances of that order.[5]
  Note: Quotation from refs. [3],[4]


Edit: Since it is mention under IUPAC definition that size lies between $1nm-1000nm$, therefore this must be the correct size.