THE SIGN of the Black Rooster -- in English it sounds like the pointer to a new pub. But in Italian, the Gallo Nero is the symbol for the wines of Italy's Chianti Classico region. And in Washington it designates the Chianti Classico wine tasting and display room, or enoteca , which recently opened in Mayflower Wines and Spirits.

Washington's enoteca is only the second to have opened outside Italy, the first being in London. Authorized by the Consortium of Chianti Classico in Florence, the enoteca carries all wines bearing the Black Rooster seal that are available in Washington. Part sales, part tasting and part educational, it is a bright, attractive room inside Mayflower's new shop at 2115 M St. NW.

Large photos, by Michael Parks, catch the color and mood of Tuscany and its people. A sample of each wine stands on a display shelf. Open cases are stacked on three sides, with priced bottles for self-service sales. Pamphlets, vintage cards and decals lie around. On one side is a wash-up sink, racks of wine glasses and a loaf of crusty bread. This is where the serious work is done. When Sidney Moore, Mayflower's owner, publicized the enoteca in her monthly newsletter, she wrote that tastings would be held on Wednesday afternoons. Tastings are now held anytime. All that Moore or one of Mayflower's in-store wine consultants ask is that the participants be seriously interested in learning more about the Chianti Classico region and its wines.

In planning the enoteca , Moore had the assistance of her father, Aaron Millman. A resident of Tuscany and the only non-Italian member to have ever been appointed to the board of the Consortium, he is a member of the technical tasting committee. This gives him a broad view of the quality of the wines of the Classico region. A sample of every bottling has to be approved by the committee before the wines can carry the Gallo Nero seal.

During a recent visit to Washington, Millman said that the Classicos are among the best values in wines in the USA today. Despite increasing labor and packaging costs in Italy, prices continue to be below those of the wines of similar quality from France or California. Of course, there are always exceptions: the enoteca is displaying the '75 Riserva, Capannelle, for $700. Liquid gold? Not quite. The wine is good, but not that good. However, the label is gold -- 18 carats worth. The '77 Riserva, Capannele, has a sterling silver label and is a more-affordable $70.

Capannelle is owned by a retired plastics producer and is an example of the renewed interest in the long-established Classico region by wealthy Italian and foreign businessmen. The prestige of owning a vineyard is benefitting the industry as a whole. Disused vineyards have been replanted, new equipment purchased and publicity created that is making Italians aware of the quality of their own wines.

Only a small number of 284 producers of Chianti Classico currently export to the United States, but with the acitivities of the enoteca and Washington's wholesalers and retailers, we should be seeing more of them in 1981.