Gray Cats: The Breeds, the Gene, and Why the Fancy Says Blue

Genetically, every gray cat is a black cat with the saturation turned down. The dilution gene, MLPH, changes how pigment granules are packed into each hair. Two copies, and black pigment reads as the soft blue-gray the fancy has called "blue" since the earliest cat shows. That is the whole mechanism. Gray is diluted black, exactly as cream is diluted orange, and the show-hall word for it is blue, which is why the breed names read Russian BLUE and British BLUE while your eyes say gray.

Because dilution is recessive, two gray parents breed true, which is part of why all-gray breeds were easy to found: the color, once fixed, stays.

Four breeds wear gray and nothing else (or nearly), and our full comparison pages map them in detail. The one-glance version: check the EYES first, then the coat. The Russian Blue is green-eyed, with a silvery DOUBLE coat that stands off the body. The Chartreux is copper-eyed with a woolly coat: France's smiling blue cat.

The Korat is green-eyed (amber cast tolerated), with a single flat coat, silver-tipped, on a heart-shaped head. And the British Blue, the blue version of the British Shorthair, is the copper-eyed heavyweight whose plush coat is officially neither woolly nor double. Two compare pages carry the full field guide: Korat vs Russian Blue and Chartreux vs Russian Blue.

Probably not, and the arithmetic is friendly about it. Purebred Russian Blues are uncommon, their studbooks are closed, and gray is one of the most common colors in the general cat population, because the dilution gene runs everywhere. A gray domestic shorthair with greenish eyes is a beautiful, ordinary, wonderful cat. A Russian Blue is a pedigree with paperwork. The visual tells that suggest actual RB ancestry: the strict green eyes, the genuinely double silver-tipped coat, and the fine-boned frame. Even all three together only make a maybe. No DNA test identifies Russian Blue ancestry. Our Russian Blue profile carries the full picture.

Two more honest notes while we are at it. Gray cats are not rare (the question arrives daily; the answer is that dilute black is everywhere). And gray tabbies split evenly between the sexes: unlike orange, nothing about gray is sex-linked.

Almost everywhere. Blue is a named class in most breeds' standards: blue Maine Coons, blue Persians, blue Devon Rexes, blue Sphynx, and the Nebelung, the Russian Blue's semi-longhaired relative, which wears the same color in a longer coat. Gray also pairs with white in the bicolor pattern (that page is its own guide) and appears as the ground color of the gray tabby. Solid gray, gray-and-white, gray tabby: same gene underneath, different patterns on top.