TWO ART SHOWS. Standing on that blurry border between art and craft

If rarity is a contributing factor to value, then a warm and sunny day in England this year is precious indeed. The first few days of The Burlington House Antiques Fair in London exactly coincided with the second half of summer, raising the temperature in the lofty galleries of The Royal Academy to the level of the prices. Space on the few velvet-covered benches was at a premium for those needing to recover from the effects of one or the other. Not that prices were much in evidence in this most prestigious fair, under the patronage of Queen Elizabeth, the Queen Mother, opened by the Prince and Princess of Wales, and displaying a choice selection of items from the royal collections. Few dealers marked the prices on tickets covered with every piece of information but the bottom line, for this is a fair for the ``serious'' collector. Casual browsing is tolerated, but it is a brave browser who inquires a price and risks a cool stare.

The organizers point to the great range of items on display, from the important pieces of museum quality to those of interest to the ``modest'' collector. Those whose modesty is too extreme for anything beyond a light lunch on these occasions might care to remember that ownership does not necessarily prove connoisseurship, and that one can be a connoisseur without a checkbook, only no one else knows it.

Heartened by this encouraging philosophy, and strengthened by a good lunch, even a half-day's cursory inspection of the loan exhibits -- the best that over 80 dealers could muster -- is a thoroughly worthwhile experience. Idle curiosity over prices may be discouraged, but few cognoscenti are unwilling to share knowledge on their favorite subjects.

This year The Burlington House Fair has gone international and invited several of the most important dealers from France, West Germany, Holland, and the United States to take part.

While this is not new to Britain -- the annual ceramic and silver fair at the Dorchester Hotel have followed this pattern from inception -- it brings Britain into line with other great European fairs such as the Paris Biennale, with which it alternates, and the Biennale of Florence. The continental taste for marquetry and ormolu tends to outweigh the traditional British taste for brown mahogany, while the American dealers bring a welcome -- and for Britons a rare -- glimpse of the antiques of the New Wo rld.

But what of our new world, that of now? The definition of the word ``antique'' in relation to fairs is becoming increasingly blurred. Strict datelines have traditionally been rigorously imposed, but these are now giving way to criteria based on quality irrespective of age, or so it is claimed.

However, there is as yet little of this century breaking through the imaginary barrier between the antique and the modern. A few pictures and the work of a small number of highly distinguished jewelers and silversmiths are the only objects of the 20th century bold enough to intrude. For a while the rival Grosvenor House Fair included some dealers in late 19th- and 20th-century works, but they were carefully segregated from the more conventional dealers. Why this exclusion?

The Burlington House Fair, like other fairs of its kind, includes works of art from the East, Middle East, and the West from ancient times to the late 19th century. It must be reasonable to say that a number of radical changes in concept and method of production have occurred during the last 3,000 years. Yet we accept that they blend harmoniously in the same surroundings. After considerations of personal taste, the criteria are always of quality and condition and seldom does the question of a difference

in age rate a thought. Are the modern works so revolutionary or even decadent that they have no place among the works of the past?

But this is not a new question. So much that is really new is often rejected by all but a few, and a loss of past standards is bewailed. We all know the reception first given to Impressionist paintings, but now they are frequently placed very successfully with 18th-century French furniture, for long the ultimate in established taste. It seems that we need time to accept that the works of our own generation are not being created on the wrong side of some great divide but are part of a continuing, if chan ging, pattern of creativity, as they always have been.