COUNT Sigvard Bernadotte, whose father was the king of Sweden and whose sister is the queen mother of Denmark, is a designer who could be expected to know what would be fit for a king.

The sterling silver ice-water jug, designed by Bernadotte in 1952, is fit not only for a king but a god.

The pitcher, shaped by a master hand, has no ornament nor needs one. The 6 3/4-inch-tall shape is almost like a heart, with a black handle set in the identation. The lid's hinge is in the middle, so carefully made that it seems a part of the lid, A strainer is set into the point, the back lifts for filling. When you pour from it, you would expect mead at the very least.

Bernadotte is one of 77 artists who have designed for Georg Jensen, the Danish silversmith wo was a pioneer in popularizing modern silver design. Works of all 77 are included in a show at the Renwick Gallery (17th Street and Pennsylvania Avenue) through July 6.

(The excellent catalogue accompanying the show also is being published as a book -- "Georg Jesen Silversmith: 77 Artists, 75 years" -- by the Smithsonian Institution Press (both in hard and paperback). The illustrated catalogue includes a foreward by Lloyd Herman, director of the Renwick; and essay by Erik Lassen, director of the Danish Museum of Decorative Art; biographies of the designers, and full notes on each object in the show.)

Bernadotte was born in 1907. He studied at the Royal Swedish Academy of Fine Arts in 1929, to the surprise of a great many people who didn't think of king's sons as working people. He was 23 when he went to work in 1930 for Georg Jensen, a collaboration that lasted a quarter of a century.

He was not the only member of the royal family to be artistic. His mother, the crown Princess Margareta, was known as a painter, and his great uncle, Eugene, was called the "Painter Prince."

His first work as a designer came when, according to the catalogue, he was chosen as the designer of a line of modern silverware to be sold by a Swedish firm. The eldest son of Georg Jensen, Jorgen, who was living and working in Stockholm, was chosen to execute Bernadotte's design.

Bernadotte at the beginning turned up his nose at the current crop of Jensen silver. The Swedish taste was much more clean lined than what Jensen was making in the '30s. Bernadotte's work, like the pitcher cited, is composed of lines so pure yet sensuous that you have to hold your hands behind your back to keep from stroking it. (There are guards at the Renwick to help you resist the impulse.)

Bernadotte's elegant cylinders, spheres and funnels, sometimes with soldered parallel fluting, were an immediate hit in the Art Moderne high-style centers of taste in London and New York. Bernadotte can be credited with moving Jensen into the modern period. Following the Jensen Line

Georg Jensen guided the silversmithy from 1904, when he opened shop, to 1935. The designers, though often strong and opinionated, still had to work within his lines. Not till Bernadotte came to the company did a break with Jensen's style come to pass.

Jensen was born at Jaegerborg Deer Park in Raadvad, a small industrial town north of Copenhagen. The catalogue quotes from his 1926 memoirs, published in a Danish art journal, The Collector:

Raadvad was a paradise on earth, the loveliest of woods with magnificent oaks and beech trees, with its large mill pond, from which the stream that drove the water mill divided itself into two arms and flowed further through the low lying meadows with the mysterious alder thicket, where the crows gathered together in large flocks just after sunset and screamed so that they could be heard from a great distance.

Jensen's father was a grinder, using the water from the stream that flowed from the woods. He worked in a foundry, and apprenticed to the brazier. The catalogue says, "Though he read widely, he was never able to write and spell correctly" because his schooling was very limited. After his parents moved to Copenhagen when he was 14, he was apprenticed to a goldsmithy, qualifying as a journeyman in but four years.

Back then workers weren't expected to need much writing and reading, but the Sunday School movement (with classes on Sunday because the young students worked during the week) was established to provide elementary education, and Jensen took advantage of it. He went on to study at a technical school, all the time working as a goldsmith.

But he really wanted to be a sculptor. Even as a boy he had modeled in clay. He met Theobald Stein, a well-known sculptor, at the Sunday School and went on to work in his sculpture studio. Finally Jensen was accepted by the Royal Danish Academy of Fine Arts (Kunstakademiet). Even though he completed the courses, he couldn't sell many of his sculptures; but one of his porcelain vases ("Girl With Jar") was bought by the Danish Museum of Decorative Arts. He had to rely on his work in the goldsmithy to support his wife and two sons. In 1900 he wond a travel award from the academy and went to Paris to study art. During this period, his first wife died.

At 40, remarried with a young daughter, he finally (with much sorrow) came to admit that he would never make a living as a sculptor; but he always called himself "orfevre sculpeteur" (silversmith sculptor), as did early French court goldsmiths. When he finally had money, he had one of his statues ("The Harvester") cast in bronze and mounted in his courtyard.

Jensen worked for a time as a foreman for Mogens Ballin, an avant-garde metal company that had revived pewter. Jensen made his first jewelry for Ballin, which was immediately bought by the Danish Decorative Art Museum. He borrowed money and set up his own shop in April 1904. In that simpler time, he hung a box of silver outside his workshop during the day hours.

Even today, as jewelry goes, Jensen pieces are distnctive but not terribly expensive. Pieces range from a key ring for $29.50 to a bracelet for $1,200. Jensen's style was in the Arts and Crafts tradition, using colorful stones that were not gem grade -- amber, opal, moonstone, malachite -- set in silver, often incorporating naturalistic elements.

Lassen quotes Henry Pilstrup, a Georg Jensen apprentice when he was 14, as recalling:

"When he [Jensen] arrived in the morning, he pulled a pile of designs out of his pocket -- they had been drawn on whatever piece of paper he could lay his hands on; sometimes he had drawn on torn-off wrapping paper. He worked quickly; in an afternoon he could fill up a sheet of sketches, all the while he sat singing his own songs to his own melodies." Glories of Silver

Two of Jensen's works in the Renwick show illustrate his style.

A sterling silver compote, hung with sculptured grapes, set upon a twisted stem looks as though it were intended for the revels of Bacchaus. Jensen designed the compote in 1918. It is a natural outgrowth of Art Nouveau. It is very much in the same feeling as the popular Acorn silver. Even today, it is voluptously beautiful.

A "tea machine" designed by Jensen in 1915 is far simpler. The pot itself is an essence of teapot. The handle has flower details at the joint, and on the top is a small crown. The burner also has a crown shape, with bulbous chased (cut) detailing. Again, his design could not be mistaken for anyone else's.

There are other glories in the Renwick exhibition. A clock, designed by Johan Rohde in 1919 of bent, chased and shaped silver -- is clearly influenced by Jensen, though not as well done. It is a very elegant Art Moderne piece.

The exquisite candlestick -- casted, pressed, chased and soldered by Rohde, in 1919 -- uses the characteristic oxidation to heighten the design. A 1926 box for gambling counters, also by Rohde, was designed with five layers, each one with a button on the inside to show how to stack them.

A mixing stainless steel, designed by Georg Schutt in 1958, is the very essence of simplicity, yet it manages to look Egyptian. (It also looks like as pizza cutter and might even work as such.)

A tea pot and water jug, also of stainless steel was handmade by Magnus Stephensen in 1957. The polish is so high and the workmanship so remarkable, it is equally desirable with silver. The two pieces stack on top of each other, meshing perfectly and forming a single composition.

A cup, designed in 1916 by Kristian Mohl-Hansen, is chased in a wonderful swooping Art Nouveau design. It is set with amber stones in the manner of Jensen's jewelry.

Ole Kortzau's handsome hand-chased and sculpted sterling vase, designed last year, is in some ways a return to naturalistic design. It looks like a fading flower bloom.

Far different is Henning Koppel's sterling desk set introducted in 1978 with black insides. A number of the great flatware designs, in silver and stainless, are included in the show. The pyramid flatware pattern is particularly handsome, though closely akin to a similar design by Tiffany. The Kalo Shops

Silver manufacturers in the United States today, Herman points out, "exhibit small interest in producing and promoting styles that are modern today. Those that do usually produce their contemporary designs in stainless steel, apparently considering that the tastes of consumers who would buy designs of the present are more attuned to steel as a material suited to a less formal style of entertaining. . . ."

The Kalo Shops, documented by Sharon Darling in "Chicago Metalsmiths" (Chicago Historical Society, 1977), are an example of an American silversmithy that has produced work of outstanding modern design. The Kalo Shops and its brethren (or rather "sistren," since many of the workers were women) started as followers of the English/American Arts and Crafts Movement, sliding into the Scandianvian style, which was its international heir. Darling, pointing out the Jensen influence in America wrote, "His work was so compelling that no modern metalsmith could ignore it."

Today, according to Susan Volk, at the Phillips auctionhouse in New York, Georg Jensen silver is highly priced. "Even with silver prices as they are today," said Volk, "people still collect Jensen. Back when silver was selling for $10 or so an ounce, Jensen was going for $40 an ounce."

A tea set in a recent silver auction at Phillips brought $14,000.

Even so, the antique price of Jensen is less than the retail prices. It's hard to get anyone to give you a firm price on any piece of silver, but the acorn pattern, the most popular, if it's in stock and doesn't have to be made up in Denmark, costs about $975 for a five-piece place setting, according to Bloomingdale's Rosemary Maloney. The scroll faltware goes up to $1,325 for five pieces.

J. E. Caldwell's and Bloomingdale's are prime local sources for Jensen silver.