Important note:
Only Chartreux cats are the true Carthusian cats, not the British Shorthair, as those are sometimes called erroneously.

History

The Chartreux is the "natural" breed of France and is one of the most ancient breeds. The legend says that in 1558 it had been reported that French Carthusian monks, who were well known for their liqueur called Chartreuse, should have bred this breed. This seems to be a mere legend.

The name "Chartreux" was first mentioned in Dictionnaire universel de commerce, d'histoire naturelle et des arts et métiers, Jacques Savary des Bruslons, 1723 ^[1]:
"CHARTREUX, Le vulgaire nomme ainsi une sorte de chat qui a le poil tirant sur le bleu. C'est une des espèces de fourrures dont les Pelletiers font négoce."  ¹⁾, Volume 1: under the entrance CHAR, page 812.

In the volume of the encyclopedia, issued 1753, the Chartreux cats are described that the colour of their coat is ash-grey, and that the coat was used by furriers (because of its thickness): Encyclopédie, ou Dictionnaire raisonné des sciences, des arts et des métiers ^[2] :
"Chartreux, (Hist. nat.) sorte de chat dont le poil est d’un gris cendré tirant sur le bleu. C’est une des peaux dont les Pelletiers font négoce, & qu’ils employent dans les fourrures.", L’Encyclopédie, Volume 3, Cha - Consécration, octobre 1753  ²⁾

In Dictionnaire raisonné universel d'histoire naturelle : contenant l'histoire des animaux, des végétaux et des minéraux, et celle des corps célestes, des météores, & des autres principaux phénomenes de la nature; avec l'histoire et la description des drogues simples tirées des trois regnes ... plus, une table concordante des noms latins ... (MDCCLXXV [1775])  ^[3], Jacques Christophe Valmont de Bomare, 1775, Volume 1, page 59
the Chatreux is mentioned in comparison to cats from other countries, like Spain, Persia, chat d'Angora from Anatolia.

As you can read there, it is speculated that the climate influences the type, coat and colour and that those cats may be a different breed.

	Jean-Baptiste Perronneau, born 1715 in Paris, died 19.11.1783 in Amsterdam, was a French painter, who specialized in portraits in pastels. Painting of Magdaleine Pinceloup de la Grange from 1747 Getty Center, Los Angeles
	Detail from the painting

In Histoire naturelle de Buffon. Histoire de la terre-t. 2. Histoire des minéraux-t. 3. Histoire de l'homme-t. 4-6. Histoire des quadrupèdes-t. 7-9. Histoire des oiseaux-t. 10. Histoire de la reproduction, ^[4], Georges Louis Leclerc comte deBuffon, T. 1, Firmin Didot Frères, Paris, 1754, Volume 4, page 222
the Chartreux is mentioned in comparison to cats from other countries, like the Persian from Chorazon (province of Persia), chat d'Angora from Syria, the cats from Spain.

Plate from the edition of 1799

In Dictionnaire raisonné et universel des animaux ou le règne animal, François-Alexandre Aubert de La Chesnaye des Bois, 1759, Paris, Volume 1 ^[5]
the Chatreux is decribed under Domestic cats:

Before WW II the Chatreux was quite well known in the Normandie, Île-de-France, where the sisters Léger, living on the island Belle-Ile, had some Chatreux. In 1933 their Chatreux Mignonne de Guerveur became Int. Champion and Best cat in a cat show organized by the Cat Club de Paris. In 1939 the first standard for the Chartreux was established.

During and after World War II the breed was in grave danger of extinction, and thus British Shorthair and Persians were crossbred into the breed around the 1960th. At that time there did not exist a consequently separate registration of British Shorthair and Chartreux, which was the reason that British Shorthair had been called erroneously Carthusian cats. In 1970 the FIFe merged the British and Chartreux and both had the same standard. The breeders Simonnet (Cattery Vaumichon) and Jaquemin (Cattery Lilas Bleus) in Paris founded the "Club de Chat des Chartreux" to save the uniqueness of the Chartreux. And due to their effort, at least in 1977 a separate standard for the Chatreux was accepted by FIFe.
But the Cat Club de Paris, founded in 1913, had put an end to this hybridization already in 1950, and from that time it was only permitted to mate Chartreux with Chartreux.
In 1972 the first Chartreux cats were exported to North America by Helen Gamon, California.
In 1987 the Chartreux was recognized by CFA and TICA.

A famous owner of Chatreux was the French novelist Colette:

Her full name was Sidonie-Gabrielle Claudine Colette, born 28.01.1873 in Saint-Sauveur-en-Puisaye, Département Yonne (Burgund), died 03.08.1954 in Paris.
The heroine in her book La Chatte, released in 1933, is the Chatreux, Saha.

General Charles de Gaulles, born 22.11.1890 in Lille, died 09.11.1970 in Colombey-les-Deux-Églises (Haute-Marne), had a Chartreux, called Ringo de Balmalon.

Temperament

Chartreux are called the "smiling" cats because of the expression of their face, emphasized by the rather small muzzle when compared to the entire head.
The Chartreux are very quiet, yet proud cats. Their eyes reveal energy and an acute interest in their surroundings.
Their voice is rather chirping and quiet, but they are very good hunters.
The Chartreux displays outstanding qualities of endurance and remote reserves of energy, they are extremely intelligent and alert cats, they are very loyal and devoted to their owners. Those qualities of silent strength have enabled that extraordinary breed to survive for so many centuries.

Grooming

Chartreux have a very dense coat, which plays an important role in breeding those cats. Thus regular grooming is strongly recommended. To give them a bath periodically is not necessary because their coat does not get smudged.

2) Translation:
CHARTREUX, (Hist. nat.) kind of cat whose hair is of an ash-gray cast on blue. It is one of the skins, of which the  furriers make trade, & which they use in the furs.