Using sol-gel auto-combustion method, Ni1-xZnxFe2O4 ferrite pigments with spinel structure were prepared. The relationship between nickel ion content and structural, colorimetrical, as well as absorbance properties was studied. Structural characterization was performed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared adsorption (IR), CIE-L*a*b colour measurements and diffuse reflectance spectroscopy. Preparation method provides nanometric pigments with monophasic spinel structure. Increasing nickel content, decreases lattice constant and shifts intrinsic stretching vibrations of the metal tetrahedral sites to higher infrared adsorption regions. The optical adsorption bands give evidence for inter-atomic transitions between oxygen atomic 2p-orbitals and iron atomic 3d (t2g)-orbitals. Nickel addition decreases the value of optical band gap. Colour measurements show that H°, C, L* values decrease with nickel ion concentrations, thus changing colour from orange to dark brown.