Particles of a polysaccharide derivative, having at least one substituent with conjugated unsaturated bonds and exhibiting an index of refraction in excess of 1.50 and a method for the production thereof. In the method, the raw-material is suspended in an organic solvent to form a suspension, which is contacted with an organic reactant comprising a residue with conjugated unsaturated bonds; the raw-material and the organic reactant are reacted to form a derivative exhibiting ester or ether bond between the raw-material and the residue with conjugated unsaturated bonds; the polysaccharide derivative is dissolved in a solvent to form a solution; and the solution is contacted with a non-solvent to precipitate particles of the polysaccharide derivative. The invention provides lightweight, optically improved organic pigments and fillers based on renewable resources and which are recyclable by combustion or composting.