A process for preparing a color stable Mn4+ doped complex fluoride phosphor of formula I includes Ax(M(1−m), Mnm)Fy  (I) contacting a first aqueous HF solution comprising (1−m) parts of a compound of formula HxMFy, and a second aqueous HF solution comprising m*n parts of a compound of formula Ax[MnFy], with a third aqueous HF solution comprising (1−n) parts of the compound of formula Ax[MnFy] and a compound of formula AaX, to yield a precipitate comprising the color stable Mn4+ doped complex fluoride phosphor; wherein A is Li, Na, K, Rb, Cs, NR4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; X is an anion; a is the absolute value of the charge of the X anion; x is the absolute value of the charge of the [MFy] ion; y is 5, 6 or 7; 0