Gazing at the almost-finished painting in the garden of his home, traditional Tibetan deity painter Shihorto ponders whether his innovations are artistically acceptable.

The colorful painting, known as a thangka in Tibetan regions, looks much like others in its genre, but the bridge of the nose of the Buddha and the navy blue pot he is holding are notably highlighted.

Shihorto says he used the effect to create a bit of a three-dimensional feel, a technique he learnt from Western paintings.

"You feel that you can get the pot from the picture," he says, raising his palm to make a grabbing gesture. The client who commissioned the work suggested the changes, but Shihorto had to make sure the innovations were minor so the traditional art form was preserved.

"The change can only be very, very small. Otherwise, the thangka will be ruined," he said.

But not every thangka painter is so conscientious.

Traditionally, Tibetan Buddhist monks and folk artists made the sacred deity scroll paintings to hang in monasteries. But today, the rising popularity of Tibetan arts in China and a wealthy middle-class appetite for thangkas has pushed market prices up ten-fold over the past five years.

As more thangkas are hung in homes or wrapped in gift boxes, the number of replicas and unscrupulous made-to-order works has grown, threatening to erode the overall quality of the art, says Nyangmo Tsering, head of culture and tourism with Tongren County government, in northwest China's Qinghai Province.

Tongren, a largely Tibetan county on the eastern edge of the Qinghai-Tibetan Plateau, is at the forefront of the battle to guard the reputation of the thangka.

Last year, the county's thangka paintings, murals, patchwork crafts and sculpture -- known collectively as the Regong arts -- were listed as the Intangible Cultural Heritage of Humanity by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Thangka painting thrives in Tongren, which has about 2,500 practitioners, and in some villages, almost every household has a thangka studio. The orders came all year around, with sale prices ranging from 10,000 to 1 million yuan a piece, practitioners say.

One reason for the high prices is that the thangka painting uses natural dyes -- ground gold, turquoise, and other precious minerals -- meant to last thousands of years.

But Nyangmo Tsering says unscrupulous painters have been found mixing chemical and natural dyes, or Xeroxing the outlines of others' work for quick cash.

"People from the outside can't see the difference," she says. "With its rising popularity of thangkas, we fear the quality is declining."

Their fears highlight the dilemma facing the protection of China's intangible cultural heritage. The damage caused by cashing in on their popularity can be the same as loss of public interest, experts say.

China has 1,028 state-level intangible cultural heritage items, of which26 are included in UNESCO's list of the Intangible Cultural Heritage of Humanity, says Vice Minister of Culture Wang Wenzhang. Some are being damaged by over-exploitation of their economic value.

Wang says national and local governments have invested at least 1.79 billion yuan in the protection of intangible cultural heritage and the urgent task is to systematically plan and meticulously carry out preservation measures.

The local government of Tongren wants Shihorto and other thangka gurus to lead the fight against fakes, copies and unscrupulous work.

An appraisal committee has been set up to review thangkas before sale, painting competitions are held regularly, and plates proclaiming "Home of a Thangka Artist" are placed outside the homes of 83 recognized artists.

Sixty years ago, Shihorto learned his art over five years at the renowned Labrang Monastery, studying sutras in the morning and painting in the afternoon. Discipline was strict. "Once the teacher hit my head until blood flowed because I had failed to memorize the sutra."

Today's young artists think they can learn it in two to three months, he says. "Now almost none of the young painters study the sutras."

Though his works sell, Shihorto seldom paints anymore and focuses on the preservation of the art of thangka.

"The art fed my family all these years and I should do something for it in return," he says. Enditem

(Xinhua reporters Cao Guochang and Zhang Zhanpeng contribute to the report)