An ink including an aqueous dispersion of a metallic pigment and a film-forming resin, optionally together with one or more of a pH-adjusting agent, a color agent, a linking agent, an anti-settling agent, and a preservative, is disclosed. A marking instrument, particularly suitable for use with an ink according to the invention, and including a low-density reservoir for storing ink joined in capillary coupling relation to a porous nib, is also disclosed.