Abstract: This invention relates to a process for the manufacture of crystal sugar from an aqueous sugar juice containing sugars and organic and mineral impurities, including Ca.sup.2+ and/or Mg.sup.2+ ions, such as a sugar cane or sugar beet juice, comprising the following operations:(a) concentration of said sugar juice to give a syrup, and(b) crystallization of said syrup to give a crystal sugar and a molasses,characterized in that it also comprises an operation:(c) of tangential microfiltration, tangential ultrafiltration or tangential nanofiltration, this operation being effected before operation (a).It also relates to a process for the production of crystal white sugar from a sugar juice of the sugar cane juice type, comprising the above-mentioned process for the production of crystal sugar, completed by re-melt, decolorization and crystallization operations.