Global demand for gems and jewelry—especially precious stones—is strong, fueled by newly wealthy buyers looking for spectacular luxury objects. Art isn’t the only market being transformed by new players from such countries as China, India and Russia; the jewelry market has undergone a sea change as well, becoming both truly international and very competitive. To cultivate the more-global clientele, auction houses are looking beyond Europe and New York to, most notably, the Middle East, where demand for high-quality gemstones is growing. And from the totals—worldwide jewelry sales at auction rose 20 percent last year, to $750 million—it would seem that buyers hailing from Hong Kong to London to Manhattan are eager to indulge their taste for glittering luxury objects.

Christie’s, the market leader in the field since 1994, took in $395 million in 2007, its highest total ever; Sotheby’s gross grew 46 percent, to $292 million. Together, the two houses accounted for more than 90 percent of world jewelry sales at auction, with their nearest rival, Bonhams, contributing just 3.5 percent and Phillips de Pury & Company and smaller regional firms like Tajan and Artcurial in Paris making up the rest.

Christie’s and Sotheby’s show no sign of losing their dominance. But as more buyers from Eastern countries enter the market, its center of gravity is shifting, with Geneva losing ground to Hong Kong, New York and Dubai.

Not that the Swiss city can be counted out. As a low-vat oasis in the heart of Europe, it remains a key hub, particularly for Sotheby’s. Traditionally, Geneva has catered mainly to the trade, but Sotheby’s estimates that 70 percent of its recent sales there were to private buyers—the vast majority of them auction neophytes. “Geneva is a destination venue,” says David Bennett, Sotheby’s jewelry chairman for Europe and the Middle East. Last year was a banner one for the firm in Geneva: It outsold Christie’s there, $97 million to $90 million, for the first time since 2000, and last November it registered its best-ever session total, of SF64 million ($57 million).

This May 15, Sotheby’s Geneva will offer an emerald and diamond sautoir from the 1930s (est. SF175–260,000; $160–240,000) and a rare 19th-century natural-pearl and diamond brooch from a British noble family (est. SF450–670,000; 400–600,000). The Christie’s Geneva sale on May 14 features two fancy-color diamonds—a 13.38-carat intensely blue rectangular-cut stone ($6–8 million) and a 21.40-carat vivid yellow heart-shapedone ($2.5–3 million)—plus a 13.72-carat cushion-cut Burmese ruby ($1.6–2 million).

Phillips, striving to establish a significant presence in Geneva, has had two years of slumping jewelry sales there. In a bid to shore up its waning clout, the firm is staging a joint sale with the Paris auction house Pierre Bergé & Associés on May 13. Highlights will include a Belle Époque diamond brooch with three large, gray natural pearls (est. SF50–80,000; $49–79,000) and a 1960s Van Cleef & Arpels ruby and diamond necklace (est. SF25–50,000; $25–49,000).

Geneva remains a vital hub of the jewelry-auction business. But its preeminence is under threat. For Christie’s, New York is the most lucrative venue, with jewelry auctions at its branch there pulling in $320 million since 2005. New York’s prominence reflects the purchasing power of American private collectors as well as the dollar’s decline against the euro and other foreign currencies, which has brought more European buyers to the city. In addition to New York, Christie’s has continued to do well in London, where the firm outsold Sotheby’s three to one last year. Its sales in Hong Kong last year totaled $96 million. Meanwhile, Sotheby’s October auction there posted HK$317 million ($40.8 million), the firm’s highest for a jewelry sale there. “The überluxury markets remain vibrant and dynamic, and the immense wealth created in the region in the past few years has translated to great buying power among the Asian elite,” says Chin Yeow Quek, Sotheby’s head of jewelry in Asia.