Patent ID: 7402200

Claim:
A cyan ink, for use in an ink set having four kinds of aqueous inks consisting of the cyan ink, a magenta ink, a yellow ink, and a black ink, in which each ink comprises at least water, a water-insoluble coloring material, and a plurality of water-soluble organic solvents having (a) a good medium or good mediums for the water-insoluble coloring material and (b) a poor medium or poor mediums for the water-insoluble coloring material, wherein: the ratio B 1 /A 1 is from 0.5 or more to 3.0 or less, where A 1 denotes the total content (mass %) of the good medium based on the total mass of the cyan ink and B 1 denotes the total content (mass %) of the poor medium based on the total mass of the cyan ink; and a water-soluble organic solvent which shows the maximum Ka value among the respective Ka values of the plurality of water-soluble organic solvents as determined by the Bristow method is the poor medium.