Lake Biwa is synonymous with pearls. Japan's largest body of freshwater, between 4 million and 5 million years old, the lake lies in the center of Shiga Prefecture, near Kyoto City. It was here that freshwater pearl cultivation first began.

Beginning in the 1890s, a flurry of Japanese researchers began to experiment with pearl cultivation, first with oysters in Mie Prefecture's Ago Bay and later with mussels in Lake Biwa.

Not until 1910 did the first cultured freshwater pearls of any commercial value begin to appear. Though not the originator of the technique, it is largely because of the commercial genius of Kokichi Mikimoto (1858-1954) that it is possible to speak of a "cultural revolution" in the jewelry industry that drove pearl ownership out of the domain of the rich few and made the single classic strand of pearls affordable for wife and working woman alike.

According to sources including the Mikimoto Pearl Island Co., Mikimoto and his associates produced pearls by inserting a piece of tissue (not a bead as in oyster pearls) into the fleshy mantle of a mussel. As would happen with a naturally occurring sand grain, this irritant acts as a catalyst to stimulate the mussel to produce a pearly substance known as nacre or mother of pearl. Mussel shells themselves are made of nacre, visible in the inner iridescent lining of each half-shell. In the case of a pearl, the progressive accumulation of many concentric layers of nacre around the invasive particle creates the distinctive iridescence or rainbow effect known as "orient," which is one of the measures of a pearl's value.

Biwa pearls appeared on the scene just when the natural saltwater pearl industry was in a serious global decline. Mikimoto's new technology dispensed with the need for pearl divers and added an extra advantage in the case of freshwater pearls: A single mussel could be seeded with multiple bits of tissue to produce as many as 20 pearls. From the consumer's perspective, at least part of the charm of these small freshwater gems called "Biwa pearls" was attributable to their unprecedented colors--mauve, peach, or heather, and their irregularities, though all were variations on a basic rice-grain shape. Designer Paloma Picasso--daughter of Pablo Picasso--was a devotee of Biwa pearls, and helped spread their popularity through her signature pieces of multiple strands twisted into single chunky necklaces known as toussades.

Even so, Mikimoto initially faced criticism on a global scale. Jewelers and consumers accused his cultured pearls of being "fake" because they were the product of human intervention rather than occurring naturally. But the genuine beauty and affordability of Mikimoto's pearls ultimately conquered the lingering resistance and for most of the 20th century Japan dominated the pearl industry. Given Lake Biwa's fame as the mother lake of these pearls, people still often refer to any freshwater pearl simply as a "Biwa" no matter what its place of origin.

The area of Omihachiman on the eastern shore of Lake Biwa had most of the pearl farms, though today their production is negligible. Most of the naiko or inner harbors where many pearl farms once operated were filled in to produce land for more rice paddies in a trend that started in the 1970s, according to Michio Kumagai, senior research scientist at the Lake Biwa Environmental Research Institute. Aside from reclaimed land, by the late 1970s, the many holiday resorts, agricultural chemicals, and industries surrounding the water began to take their toll on the lake, and the center of gravity of the pearl industry shifted to China.

But pearls or no pearls, homage to Lake Biwa is probably as old as the human communities that settled along the lakeshore about 20,000 years ago.

According to the origin myth of the lake, Mt. Fuji and Lake Biwa are deeply connected. After a thunderous earthquake and torrential rains, the skies were said to have cleared and revealed an immense sheet of blue covering the land while simultaneously on the distant Suruga plain the mountain we know as Mt. Fuji exploded into existence. From a hilltop in the Omi domain (present-day Shiga Prefecture) amazed observers noticed that the shape of the lake resembled the Chinese four-stringed lute called a "biwa" in Japanese, from which the serene body of water derives its name.

Lake Biwa is home to four islands--Chikubushima, Okishima, Takeshima and Okinoshiraishi. Only the second has a sizable community, while the first, located in the central northern part of the lake, is a major pilgrimage destination. Chikubushima's eighth-century Buddhist temple of Hogonji enshrines both Kannon and Benzaiten. The latter is a deity of eloquence and music (usually depicted with a lute in hand), and her original Sanskrit name means "one having water." Indeed, today Lake Biwa provides water for 14 million people in the region.

The lake and the region of the Omi domain were immortalized in poetry long before pearls entered their history. By the 17th century, the Omi Hakkei (Eight Views of Omi) had become a literary and artistic convention. The ukiyo-e master Utagawa (or Ando) Hiroshige (1797-1858), for example, produced his own Omi Hakkei, a series of landscapes focused on scenic spots along the southern shoreline.

The subject of art and poetry, and the foundation of human sustenance for millennia, Lake Biwa, fed by hundreds of brooks and rivers and home to over a thousand species of plants and animals, is truly Japan's mother lake. In every season but winter it is possible to ride a bicycle around the entire girth in two days. But in winter, when the snows deepen and the northern passage is forbidding, Lake Biwa can just be admired. It often glows then with the iridescent serenity of a giant pearl.

Whelan is a cultural anthropologist and author who resides in Kyoto.

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Information

--Lake Biwa Museum

Open 9:30 a.m.-5 p.m. (closed Mondays). From JR Kusatsu Station, take Karasuma Hanto bus. (077) 568-4811. www.lbm.go.jp/english

--Sagawa Art Museum

Open 9:30 a.m.-5 p.m. (closed Mondays). (077) 585-7800. www.sagawa-artmuseum.or.jp/

Special exhibition (Feb. 18-April 8): Shiga landscape artist Brian Williams. Get off at JR Moriyama Station.

--Keihan Biwako Kisen boat tours (077) 524-5000. www.biwakokisen.co.jp

--Biwako Visitors Bureau (077) 511-1530. www.biwako-visitors.jp/

(Jan. 15, 2012)