Emerald is a vibrant and strong green ink by Robert Oster. It shades very well, going from a dark green to a light green. It feels slightly drier in my Pilot fountain pen but it might be due to the pen and ink combination. Emerald is one of the best shading greens I’ve seen in a while. If you are looking for a vibrant green that has a ton of personality you can’t go wrong with Robert Oster Signature Emerald.