Metasurfaces with the capability of spectrum manipulation at subwavelength can generate structural colors. However, their practical applications in dynamic displays are limited because their optical performance is immutable after the fabrication of the metasurfaces. In this study, we demonstrate a color-tunable metasurface using numerical analysis. Moreover, we select a low-refractive-index dielectric material, Si3N4, which leaks the electric field to its surroundings. We investigate the potencial of these metasurfaces by simulations to achieve color-tuneable devices with encrypted watermarks. This modulation of colors can be applied to encrypted watermarks, anti-counterfeiting, and dynamic displays.