The black pearl of Tahiti is at the heart of French Polynesia's economy but is now highly vulnerable to climate change, and its fragile existence underlines - in a small but exquisite way - what is at stake in UN climate talks starting in Paris this month.

"We would be much happier not to have to deal with climate warming," said Teva Rohfritsch, the minister in charge of what is dubbed the "blue economy".

"Nature always adapts," he said, "but we will have to put forward measures to protect our ecosystem."

The Tahitian pearl -- its proper name is "pinctada margaritifera" -- is more commonly referred to as the silver-lipped pearl oyster after the species from which it is harvested.

Though jewel enthusiasts -- and marketing firms -- have branded it the "black pearl" of Tahiti, it is neither black nor from Tahiti.

The biggest island in French Polynesian, renowned for its exotic blue-green waters and white sandy beaches, is not the pearl's home: it is actually harvested in the tiny islands of Tuamotu and Gambiers to Tahiti's southeast.

Officially about 1,300 people toil in farms to unearth this freshwater beauty, but the sector actually counts between 5,000 and 8,000 workers, which allows remote atolls to maintain their population.

The pearl has propped up French Polynesia's economy, bringing nearly 74 million euros ($80 million) to the islands' coffers in 2014, which represents about 70 percent of its export earnings from goods.

The majority of those sales were from trades with Hong Kong (49 percent) and Japan (46 percent).

It is for this reason that the Polynesian government has taken this environmental threat from climate warming so seriously.

- Water temperature 'essential' -

It has since launched a research and development programme co-financed by the industry's private companies.

The problem was first studied 15 years ago, when the government called upon scientists to study the pinctada's quality and colours, which can vary from pink, purple, blue, green, champagne, and grey.

More recently, those scientists were tasked with finding solutions to offset the effects of climate change.

They dealt with the "increase in temperature and acidity of the water," explained Gilles Le Moullac, a research scientist with the Centre Ifremer of the Pacific, in Vairao.

The main question at the heart of the centre's research is "Would the species be able to survive?" Le Moullac said.

Inside the centre's buildings, oysters were submerged into baths set according to what warming experts at the Intergovernmental Panel on Climate Change (IPCC) believe ocean PH levels will be in 40-50 years and in the next century.

The results have proved encouraging.

"We have noticed no impact on the pearl's development," said Le Moullac.

He believes the pearl is protected by its inner shell, even if its outer shell has seen slight damage.

However, it is the rise in the ocean waters' temperatures that is more alarming.

The pinctada is at its "optimum" quality in waters that are at 28.7 degrees Celsius (84 degrees Fahrenheit), Le Moullac said.

IPCC researchers tested scenarios where they raised water temperatures by 2.0 degrees Celsius, Le Moullac said, and found that the pearls were too warm.

The temperature at which they can no longer survive is 34 degrees Celsius (93 degrees Fahrenheit).

In essence, "the water temperature is essential," said Aline Baldassari, a trader who is president of an association that promotes the pearls.

"The waters in the Gambiers are fresher than the waters in Tuamotu, which give the pearl (from Gambiers) a superior quality," she said.

- Moving further south? -

The pearl from Gambiers, however, takes a longer time to harvest -- between 22 and 24 months versus 16 to 18 in Tuamotu, Baldassari added.

Adding to that are issues of a "bloom" of algae that have suffocated lagoons and have proved fatal for the pearls, just like in the Takaroa atoll in 2013-2014.

Research began in Vairao to determine whether the explosion of algae was related to climate change or to pearl farmers' activities related to over-exploitation and improper trash disposal in the lagoons.

What has emerged from the research is the notion of moving the pearls that grow in Tuamotu further south to the islands of Australe.

"They are too warm," said Bran Quinquis, a general administrative counsel of climate change.

"The waters there are a bit colder and the lagoons are available," he added.

Another, less dramatic solution could come from the islands of Marquises. The research centre there found a sub-species of pinctada margaritifera that is used to warmer waters.

"It brings hope," Quinquis said.