The invention provides a method for the production of a luminescent material, (10) based on coated quantum dots (100), comprising: (i) providing luminescent quantum dots (100) in a liquid medium (20) wherein the luminescent quantum dots (100) have an outer layer (105) comprising first cations and first anions; and (ii) providing in a coating process a coating (120) on the outer layer (105) of the quantum dots (100) in the liquid medium (20), wherein the coating (120) comprises a silica coating; wherein during the coating process, or after the coating process, or during and after the coating process, the liquid medium (20) comprises one or more of a third element and a fourth element, wherein the first cation and the third element belong to the same group of the periodic system, and wherein the first anion and the fourth element belong to the same group of the periodic system.