Emeralds shaped like giant tear-drops, rubies and sapphires carved like fruit, rows of rare natural pearls, platinum pavéed with diamonds — that is the irresistible stuff of period jewelry. Megawatt diamonds have contributed greatly to the booming jewelry market: In 2010, Christie's and Sotheby's each generated more than $400 million in sales in the category, more than double their take a decade earlier. But it's not just jaw-dropping rocks and fresh-from-the workshop pieces that buyers want. Savvy collectors are making statements with a 19th-century Boucheron choker, an Egyptian-influenced
Art Deco bracelet by Cartier, or a gold and citrine Buccellati cuff from the 1960s.

Roughly considered anything created from the 1800s to the early 1980s, period pieces can constitute between 40 and 60 percent of the lots in jewelry auctions. Generally speaking, auctioneers and dealers in New York, London, Geneva, and Paris have the largest inventory of such items.

The allure of older gems is not unlike that of antique furniture or vintage couture. "Newly manufactured material just doesn't have the same cachet," says Virginia Salem, Bonhams's New York-based director of jewelry. As Nicolas Bos, a CEO and the worldwide creative director of Van Cleef & Arpels, says, "The great thing about jewelry is that it lasts. You have something in very good condition that you can wear exactly as a new piece, but it still has the history." Buyers are often willing to pay a premium for pieces worn by royalty or stars. This December Christie's is holding a two-day sale of jewelry from the collection of Elizabeth Taylor. The provenance is important not only as a justification of your investment, says Bos, but "it also makes you feel that you're part of a succession of generations that shared the same taste. That's a very strong feeling."

The sophisticated design, extraordinary workmanship, and quality materials that characterize fine period jewelry are very seldom replicated today. As Lisa Hubbard, chairman of the North and South America International Jewelry Department at Sotheby's, explains, in previous eras each piece was expertly crafted over weeks if not months. "At Cartier, Van Cleef & Arpels, Boucheron, Chaumet, or any of the other great houses, designers had more time to develop and reflect and think and create, and they had the workmen who could actually execute their designs," says Hubbard. "They weren't dealing in volume."

Uniqueness, she adds, is a primary motive in bidding up such treasures: "One of the things I find clients talking about these days is wanting to wear something that they don't see everywhere they go. Period jewelry absolutely fits that, and the buying audience for it has increased tremendously."

Naturally, as appreciation for period pieces has grown, competition has become fiercer for prized eras and styles like the Belle Epoque and Art Deco, with dealers snapping up examples whenever they can. "The trade is very interested in older jewelry right now," says Ann Lange, vice president and director of Doyle New York's jewelry department. "It's harder and harder to find, so if there is something fresh to the market, they all jump on it."

"There was only so much produced," says Rahul Kadakia, head of the jewelry department at Christie's New York. "Back in the 1920s you might have seen 10 of something. Now we see one." Because of the decreasing supply — and consequent rising prices — of early 20th-century pieces, many collectors are turning to examples from later decades. Specialists note that jewelry from the 1950s to the '70s, in particular, has become more fashionable over the past decade.

Following is a discussion of the history, character, availability, and values of four period-jewelry categories that are among the most coveted by collectors pursuing the ultimate in vintage chic.

BELLE ÉPOQUE

The Belle Epoque (1890-1914) was marked by exuberance, frivolity, and extreme wealth. London society shed the restraint and decorum of the Victorian age, developing a taste for wispiness in clothing and jewelry. It was around this time that many of today's top gem firms made their names, including Cartier, Van Cleef & Arpels, and Tiffany & Co. All were eager to provide wares to Gilded Age patrons. "It's by far the most glamorous period," says David Bennett, Sotheby's international jewelry chairman for Europe and the Middle East. "Fashionable women were essentially covered with jewelry." Many were aristocrats, adding an element of fantasy for today's collectors. Last May, Sotheby's offered one of the most significant period pieces to hit the market in decades: a tiara once owned by the Prussian princess Katharina Henckel von Donnersmarck, with 11 rare Colombian emeralds cut and set as pear-shaped drops. Estimated at $5 million to $10 million, it brought $12.7 million.

Most pieces from this period were crafted in platinum. Louis Cartier pioneered the use of the material in the early 1900s, a technological advance that helped catapult his firm to the forefront of the field. Having greater tensile strength than gold, the metal allows for more open and delicate designs. The hugely popular Garland style took full advantage of this quality, arranging diamonds, platinum, and natural pearls in designs based on flowers, leaves, bows, and ribbons. Garland neckwear was particularly fashionable. Many such pieces were designed to serve multiple uses. Chokers, for example, could be transformed with a click or two into a tiara or bracelets. At the International Fine Art and Antique Dealers Show at the Park Avenue Armory in New York this month, the London period-jewelry dealer Sandra Cronan is offering a circa 1910 French diamond and natural-pearl choker that snaps apart to form two bracelets, priced at £85,000 ($139,000). Its natural pearls, which were used in abundance in Belle Epoque jewelry, are lure enough to draw serious suitors. "Because the world's seas are just too polluted now, there are no more pearls of any size or quality coming out of the oysters," says Cronan. The London dealer Hancocks has a circa 1910 natural-pearl and diamond sautoir with a removable pearl tassel pendant by the American firm Udall & Ballou that is priced at £25,000 to £50,000 ($41-82,000) .

At the top end, Belle Epoque pieces can cost up to $500,000, depending on the materials used, the design, and, especially, whether they bear a signature —an infrequent feature that can add anywhere from 20 to 40 percent to the value of jewelry from any period. Smaller unsigned pieces can be had for as little as $5,000. Last October a circa 1904 Cartier bow-shaped diamond brooch brought $374,000 at Christie's New York. This past June, Bonhams New York sold a natural-pearl and diamond "sautoir" from circa 1910 by the Philadelphia designer J.E. Caldwell for $39,000. "We can't get enough from the Belle
Epoque," says Salem, of Bonhams. "People inherit pieces from the early 1900s, and if they are signed, if pristine and in original condition, it's very exciting."

ART DECO

In stark contrast to the ultra-feminine Belle Epoque, Art Deco is characterized by rows of boldly colored baguette-shaped stones arranged in crisp geometric patterns inspired by the Machine Age or in exotic floral and animal designs reflecting the fascination in the 1920s and '30s with Egypt, Persia, India, and China. The liberated spirit following World War I brought a design revolution in everything from furniture to fashion, and Art Deco has long been the most sought after of all period-jewelry styles. "It was the best time of jewelry manufacture," says Kadakia, of Christie's. "You see Cartier, Boucheron, Bulgari, Van Cleef & Arpels — every major house coming up with its best creations." What set these decades apart, he adds, is that "the mood to spend had come upon the world. Royal families from India started visiting Europe. The maharajas would go to Cartier and Boucheron with trunks of loose gems and say, ‘Make me some jewelry.' That surfeit of stones is something we don't have today, and it gave designers great freedom."

Platinum continued to predominate for settings, while for decorative elements onyx and coral came into use, often combined with gemstones to create dramatic juxtapositions of color and texture. The result was a bold yet sleek aesthetic that continues to woo collectors. It is exemplified by a 1923 Van Cleef & Arpels bracelet with a woven geometric pattern composed of diamonds and emeralds surrounded by onyx that Hancocks is offering for £50,000 to £100,000 ($82-164,000). In the Important Jewels sale at Christie's London this past June, 41 Art Deco gems sold for from £5,000 ($8,200), for an unsigned circa 1930 emerald and diamond ring, to £1,150,050 ($1.9 million), for a circa 1928 Cartier Tutti Frutti bracelet with carved rubies arranged in a flower-and-vine motif, which tripled its estimate. Cartier produced only about 50 bracelets in the Tutti Frutti design, which consists of colorful carved gems resembling bits of fruit. It was created by the master designer Henri Picq as an homage to the luscious patterns found in the art and design of India, where many of the stones originated.

Although unsigned Deco pieces are more readily available, they can still fetch extraordinary prices: A circa 1920 platinum and diamond chain estimated at $50,000 to $70,000 brought $452,500 at Doyle New York his past April. "Art Deco continues to be very strong," says Doyle's Lange. "These pieces tend to hold their value — especially if they are signed."

MIDCENTURY

With the scarcity of older pieces and the increasing appreciation for vintage fashion, many collectors have rediscovered the 1950s. This past April, a circa 1950 Cartier gold, platinum, emerald, ruby, and diamond bird brooch (est. $30-50,000) brought $80,500 at Sotheby's New York. "It's very, very chic and very unique," says Doyle's Lange, who notes that designs by Van Cleef & Arpels, Cartier, and Jean Schlumberger — the French master designer hired by Tiffany & Co. in 1956 — pique special interest in the salesroom. Marked by the ebullience that erupted at the end of the World War II, during which platinum had been requisitioned for munitions, gold was scarce, and the major gemstone trade routes interrupted, this decade saw a boom in innovation and creativity by Van Cleef & Arpels, Tiffany, Oscar Heyman, and a bevy of others. "There was a complete joy fest," says Hubbard, of Sotheby's. "Jewelers went from making these spare, polished bold pieces in the 1940s to suddenly putting braids and tassels and knots on everything. It is very wearable and very desirable now."

Christian Dior's glamorous New Look was all the rage, and proper ornamentation was required. "The wide-brimmed hat, the full skirt, and a fabulous pair of earrings or double-clip brooches to hold down the neckline of a dress or sweater — this is one of the most incredibly chic looks," says London dealer Cronan, who has a pair of circa 1950 carved-emerald and diamond ear clips. Although the classic bold cocktail rings and cluster earrings from this period can be had for less than $5,000, many pieces are encrusted with precious gems, and are priced accordingly. Diamond grading was standardized in 1957, leading to generous use by such firms as Harry Winston, whose opulent stone-on-stone chandelier earrings and bibs of diamonds are still appreciated, if not so easy to wear. The decade was also marked by technical innovations. The Van Cleef & Arpels "mystery" setting, for instance, in which the prongs are hidden, was invented in 1933 but perfected during the '50s.

Another midcentury characteristic is unusual combinations of diamonds, emeralds, citrines, and peridots, as well as turquoise, coral, and chrysoprase. One supreme proponent of this mixing and matching was Tiffany's Schlumberger, who is also known for reviving "pailloné" enamel, in which layers of translucent enamel are applied over gold leaf. He used the technique to create the bracelets, brooches, and earrings that became a Jackie Kennedy staple in the early '60s. His designs are still fabricated by Tiffany today, but the older examples nevertheless consistently surpass their estimates at auction: A diamond, blue-enamel, and gold brooch that he made for Tiffany around 1955 (est. $7,000-$10,000) brought $20,000 at Christie's New York last October.

1960s AND '70s

The biggest shift in taste over the past few years, specialists agree, is toward designs from the late 1960s and the '70s. "Yellow-gold, very artistic, chunky jewelry has really come back," says Chris Del Gatto, CEO of the New York-based private estate-jewelry dealer Circa. "People are not looking to be dripping in diamonds as much anymore." Signed pieces by Van Cleef & Arpels, David Webb, and Cartier are especially in vogue right now, adds Del Gatto, who is offering a 1960s David Webb 18-karat-gold cuff in the shape of a panther with small emerald eyes that retails for around $30,000.

Jewelry from this period affords boldness without excess, a plus in the wake of the recent recession, when conspicuous displays of wealth became unfashionable. With gold prices now rising, 18-karat pieces are particularly attractive as investments. Designers during the '60s and '70s used the metal not just for settings but also as the focal point of their pieces. Many looked east for inspiration, mimicking India's swirling paisley patterns, for instance, or reviving the exotic animal motifs popular in Art Deco. Swaths of textured gold, hammered, stippled, and twisted, on their own or paired with such materials as wood, coral, and tortoiseshell, are highly desirable. A pair of 1971 Van Cleef & Arpels gleaming wood and gold bangles, well suited to the clean lines of clothing designed by Halston, doubled its high estimate of $5,000 to bring $11,250 at Christie's last fall.

Such longstanding firms as Buccellati prospered in the '60s and '70s, opening up international boutiques and drawing customers with textured-gold rings, bracelets, and necklaces that "women can't get enough of today," says Salem, of Bonhams, which last April sold a large Buccellati citrine and 18-karat-gold ring, estimated at $1,200 to $1,500, for $5,800. "A lot of women are going for that one bolder, chunkier statement piece." Also hot are examples by the English artisan Andrew Grima, who made wild, rough-hewn rings and necklaces set with lumps of minerals for swinging Londoners as well as British royals. Primavera Gallery, in New York, has a pearl and topaz necklace by Grima for $30,000 to $40,000.

The free-spiritedness of the period is reflected in the organic forms of hoops and long necklaces, and high-end examples of bohemian chic can score big sums. Last May at Sotheby's Geneva, a long 1970s Van Cleef & Arpels coral, emerald, and diamond necklace with matching bracelet brought SF206,500 ($233,000) against an estimate of just SF28,000 to SF48,000 ($30-50,000). It was a simpler look, says Hubbard. "Not everything was polished. Stones were used more for color. It's far easier for women to wear it today."