How do you rank a fine artist who's not quite at the top?

Every painter who succeeds dramatically has three or four close contemporaries who almost, but not quite, follow him all the way up the ladder to fame and glory.

At times these artists may come very close to real fame themselves. Their paintings may enter the collections of great museums, numerous articles and even a book or two may be written about them, and the art world may not only know of them, but may actually hold them in considerable esteem.

Even so, that last step toward true fame eludes them. In most cases it is simply a matter of not having quite what it takes. In one or two others, it can be chalked up to bad breaks. But then there are always those few for whom the reasons are more complex.

Enrico Donati belongs in the last category. Although known and respected in the art world for 40 years -- he had his first one-man show in New York in 1942 -- and widely collected here and abroad, he has never quite made it onto the very top rung of contemporary American art.

My own feelings about this are mixed. I can remember paintings of his hanging next to works by de Kooning, Pollock, and Kline way back in the 1950s that seemed as ''crucial'' and ''on target'' as theirs -- if also a bit more sensuous and elegant. And then again I have, over the years, seen canvases of his that struck me as little more than first-rate decoration. All this has left me a little confused, and has prevented me from coming to any clear conclusions about his art as a whole.

I was pleased, therefore, to note that the Staempfli Gallery here had scheduled an exhibition of 10 very recent Donati paintings. And I was even more pleased to note, when I saw them, that most of them were excellent -- and that two were quite simply superb.

Donati has always been extraordinarily sensitive to texture and surface, to the manner in which rough sand and plasterlike surfaces can evoke images of geology -- of underground rocks, fossils, runelike traces of running water, and ground-up particles of shells and shale. He has also been very alert to the way such realities can be related to flatter and more straightforwardly coloristic areas to evoke space, skies, even infinity.

Donati's textural sensibilities and his ability to evoke the qualities of natural elements without actually describing them are beautifully demonstrated in 'Blue Gray Oasis'' -- the most successful and moving painting of his I have ever seen. To create it, he took rough, textured material and paint -- then built up, gouged, molded, and annotated the surface of this work to fashion an image that projects a profound sense of endless geological time, evokes memories of fossils, of shells found in shale, of the scribblings found in caves, etc. -- and yet also moves us with aesthetic qualities derived totally from 20th-century cultural experience.

This painting, and most of the others -- with ''Oasis With Black Lake'' serving as another particularly fine example -- prove to my satisfaction that Donati should rank higher in the contemporary art scene than he does. Even if he does not end up the art-historical equal of Pollock, Rothko, Still, etc., he definitely deserves, at his best, to hang beside them on our museum walls.

At the Staempfli Gallery through June 4.