Robert Oster Crystal Marine "Shake 'N' Shimmy" ink. A deep green ink with shading and blue shimmer.
50ml bottle of fountain pen ink in a hard plastic, screw cap top from Robert Oster - Australian ink manufacturer.
Note: Shimmering inks have particles (some larger than others) that, while beautiful, can clog fountain pen feed systems. Shake the bottle before filling, and gently roll or shake your fountain pen before writing to stir up the particles. Exercising care in fountain pen maintenance and consistent use will help keep your pen happy!