The present invention relates to production method for nanoparticles used for light valves of different colors, light valves of different colors and application thereof. The light values comprise: a first transparent substrate, a first transparent conductive layer, a light modulating layer, a second transparent conductive layer and a second transparent substrate, the light modulating layer comprises a dispersion liquid and a nanoparticle dispersed-phase dispersed in the dispersion liquid; The tinted states of the light valve are displayed as multiple different colors in the visible spectral region, the bright state is colorless and transparent, and the multiple different colors of the light valve are realized by mixing nanoparticles of same or different color to form a mixture in the form of the nanoparticle dispersed-phase.

The pigment composition contains the isoindoline compound represented by formula (1) below and the isoindoline compound represented by formula (2) below. In the formulae (1) and (2), R.sub.1 to R.sub.4 represent hydrogen atoms, R.sub.5 and R.sub.6 each independently represent alkyl groups, and A and A represent a group represented by formula (3) below or formula (5) below. In the formula (3) and (5), X represents O or NH, R.sub.7 represents an alkyl group or an aryl group, and R.sub.10 to R.sub.14 each independently represent hydrogen atoms, halogen atoms, alkyl groups, alkoxy groups, aryl groups, aryloxy groups, thioalkyl groups, or thioaryl groups, ##STR00001## ##STR00002##