In 1994, when Edouard Meylan turned 18 years old, his parents gave him an Audemars Piguet Royal Oak wristwatch housed in a 33-millimeter case made of tantalum, a rare and hard metal with an unusual blue-grey sheen.

To Mr. Meylan, now chief executive of the independent watchmaker H. Moser & Cie, the watch, which came on a two-tone steel and tantalum bracelet, was something of an enigma.

“It had two colors: light gray and dark gray,” he said on a recent phone call from Moser’s headquarters in Schaffhausen, Switzerland. “I kept wondering which metal is which? Why is it so heavy?

“I kind of fell in love with tantalum. It became a dream of mine to create our Streamliner model in a tantalum case and bracelet.”