GENEVA, Switzerland — The common denominator to attract female clientele in the luxury watchmaking industry has so far usually been a sparkly one — diamonds. Vacheron Constantin, the oldest Swiss watchmaker in continuous operation, plans to change that.

As wealthy women become more important clients for the brand, their increased knowledge of elaborate watch mechanisms called “complications” has shifted their interest from the exterior to the interior, Vacheron Constantin’s chief executive officer said. Such features go beyond the simple display of hours and minutes, and include moon phases, chimes and calendars that adjust for leap years.

Women “want mechanics,” Juan-Carlos Torres said in a Jan. 21 interview. “They are asking for more now. We have to answer to their demand. For us, the next target in the future is to avoid diamonds and focus on complications.”

Swiss luxury watchmakers are increasingly producing more timepieces targeted at women, and a common strategy is offering diamond-laden timepieces with battery-powered mechanisms rather than self-winding ones, so that the watches can be smaller. IWC Schaffhausen, whose slogan is “Engineered for Men,” last year introduced its first Portofino models with women in mind, some featuring diamonds. Parmigiani Fleurier this year presented its Tonda 1950 Squelette line and splashed diamonds on the female version.

Watch companies are increasingly reaching out to women to widen their customer base. The Swiss watch industry is exiting what probably will rank as the second-worst annual performance since 2009. Full-year data isn’t out yet, but exports of Swiss watches rose 2.3 percent in the first 11 months of 2014, a far cry from growth rates that reached as much as 22 percent in 2010.

Vacheron Constantin, which turns 260 years old this year and is part of Cie. Financiere Richemont SA, presented the first female model of its Harmony Chronograph line at this week's Salon International de la Haute Horlogerie in Geneva. While the 69,500 franc ($81,000) timepiece's bezel is decorated with 1.20 carats of diamonds, future watches designed for women will focus on mechanisms on the inside rather than the outside.

“We’ll continue to focus on women,” Torres said. “The ladies like it, it’s like a piece of art.”

By Corinne Gretler. Editors: Celeste Perri, Thomas Mulier.