Something has happened in California. The big wineries are making fine wine, and the small ones, which have been making it for some time, are feeling the competition. The result should be more stable prices for the consumer and better wine on tables everywhere.

For years, discussion of California wine was dominated by the so-called "boutiques" -- small wineries that have a limited production and a commitment to quality. In the early '70s, the boutiques were the first to employ idealistic young winemakers who boldly experimented with new techniques, often with spectacular results. Costly new French oak barrels were to them what rails were to the Vanderbilts. Boutique wines, if they weren't great, were always interesting -- and expensive.

The bigger wineries lost press coverage to the boutiques, and some lost market share as well. Big became associated with bad -- sometimes justifiably.

Meanwhile, a few big producers have continued to make good wine. The Robert Mondavi Winery, for instance, set some high standards in Napa wine- making two decades ago. In the '80s, Mondavi came up with a new wine -- Opus One -- that out-boutiqued the best of them. Opus One was very expensive and heavily promoted, and some wine writers -- myself included -- took it to task for that. But Opus One is very good, and it caused a major reevaluation of California's cabernets and cabernet prices.

Another big and creditable producer of fine wine in Napa is Beringer, founded in 1876 by German immigrants. Beringer's palatial Rhine House, a 17-room stone mansion outside St. Helena, is a Napa landmark and tourist attraction. Beringer's more serious business is conducted across Highway 29, where a sprawling winery puts out about 400,000 cases of wine a year.

In 1970 Beringer was bought by Nestle. Since then, Beringer wines have been improving steadily, although for the most part they have remained in the collective shadow of the boutiques. The fact that Beringer also makes a jug wine, Los Hermanos, has not helped it in the eyes of the critics, who sometimes assign guilt by association.

Beringer has continued to invest in good equipment and good grapes. Veteran winemaker Myron Nightingale's experiments with cabernet and chardonnay were taken over in 1984 by his assistant, Ed Sbragia, who is thoroughly familiar with Beringer's diverse vineyards. Today Beringer wines in general are well made and reasonably priced. The Reserve cabernet and chardonnay are among the best California examples of those varietals. The Reserve cabernet is a blend of grapes from four vineyards and has an intense, berryish quality and loads of flavor. The chardonnay, made from grapes grown in the cooler southern end of the Napa Valley, is a highly drinkable, subtle wine with a touch of oak.

Next door to Beringer is Christian Brothers, for years associated with busloads of tourists who line up for a free taste of undistinguished wine. But the image is changing. Christian Brothers has a new management team, and the winery's distinctive Greystone mansion is scheduled for grand reopening this summer. There will be a new emphasis on quality, and no more wine-swilling day-trippers.

The new Christian Brothers '85 chardonnay is balanced and surprisingly fresh. If this is an indication of the winery's new direction, then things are looking up for the Brothers, and for the American wine drinker in general. ::