Korat vs Russian Blue: One Coat Apart, Literally

Somewhere right now a shopper is looking at four silvery-grey cats and one word, "blue," and guessing. This page is the anti-guess: the Korat and the Russian Blue differ on exactly the traits every registry writes down, and two of those traits run in directions that surprise people. We read the registries on both sides; here is the field guide.

The coat: the one word every registry agrees on

This is the sharpest contrast in the whole grey-cat family, and it is not a nuance: the Korat wears a SINGLE, close-lying coat, the Russian Blue a DOUBLE coat standing away from the body, and every registry document we read for either breed uses that exact single-or-double vocabulary on its side. Run a hand against the grain: the Russian Blue's plush springs back, the Korat's lies flat and glossy. One trait, stated by every source, and you can check it in a stroke.

Eyes: green on both sides, with one leniency

Both breeds ask for green eyes, and the difference is in the fine print: the Korat's standards tolerate an amber cast, a leniency written into every Korat document we read; the Russian Blue's standard is strict green, no tolerance clause. A grey cat with amber-leaning eyes can still be a standard Korat; on the Russian Blue side that latitude does not exist.

The head: the Korat's unshared marker

Every Korat registry, plus CFA's own three-breed comparison article, describes the heart-shaped head, the breed's single most distinctive and most redundantly sourced marker, formed by the curve of the skull and the line down to the chin. No other grey breed's standard describes anything like it. Size will not help you instead: the two breeds' weight bands genuinely overlap, and no honest page sells you a size test.

What the registries do NOT say

Three absences worth as much as the contrasts. No registry document anywhere states an outcross or breeding relationship between the Korat and any of the grey look-alikes: both breeds are closed books (unlike the Russian Blue's genuine, documented relationship with the Nebelung). TICA's own "Similar Breeds" field for the Korat names the Khaomanee, its Thai compatriot, not one single "blue cat": the grey-cat confusion is a shopper phenomenon, never a registry-curated family. And the Korat's flagship health story, the GM1/GM2 DNA-screening program running since 1998, has no Russian Blue equivalent: it is the Korat's own history, and a Korat breeder can be asked for that paperwork by name.

The other two greys, quickly and precisely

Chartreux: the one pairing where the eye rule flips completely. The Chartreux demands gold-to-copper eyes and DISQUALIFIES green; the Korat demands green. A mutual, opposite-direction disqualification: each breed's correct eye color would end the other's show career. The Chartreux also runs meaningfully heavier, wears a double, slightly woolly coat, and is the one grey where weight is a real axis.

British Blue: not a dedicated breed at all, by CFA's own history sentence, but the blue color variety of the British Shorthair, with gold-to-copper eyes and a coat its own standard explicitly rejects being double: a THIRD coat category. It is also the biggest cat in this line-up by a wide margin, males reaching 17 lb. CFA's own judge-authored three-breed comparison ("Got the Blues?") deliberately excludes it because the British Shorthair is not exclusively blue; we respect that framing rather than flattening four unequal things into one table of equals.

The grey family on one card