In fact, 90 percent of the world’s pink diamonds come from the mine, although such stones are only a tiny percentage of Argyle’s total production. The majority of its production consists of brown diamonds, which are less valuable. The mine is the world’s largest producer of diamonds by volume.

Mr. Arnaud Soirat, head of copper and diamonds for Rio, told Bloomberg that operations will be shut down in late 2020. By then it’s expected that its supply of economically viable stones will have been exhausted.

Mr. Pat Godin, CEO of Stornoway Diamond Corp., has predicted that with the closure, “The rational offset between supply and demand should lead to price growth.”

He told Bloomberg that the effect could be “even more dramatic” for pink diamonds.

“You can imagine the laws of supply and demand will apply, and you can imagine the impact that will have on those very rare pink, red, blue and purple diamonds,” Godin said.