With "101 Secrets," Jaeger-LeCoultre reaffirms the unique alliance between High Jewelry and fine watchmaking through the Calibre 101—the world’s smallest rectangular, manual-winding mechanical movement.

This limited-edition model—with only three pieces being produced—combines pink sapphires (in shades ranging from intense cyclamen to pale pink) with diamonds and 18-karat pink gold.

First introduced in 1929, Calibre 101 is the world’s smallest rectangular calibre: measuring 14 mm in length, 4.8 mm in width, and 3.4 mm in thickness (a volume of barely 0.2 cm³), it is composed of 74 parts and weighs just one gram—equivalent to the weight of two butterflies. The balance wheel oscillates at 21,600 vibrations per hour (a frequency of 3 Hertz), and the mainspring provides a 33-hour power reserve.

Created without the aid of computer-aided design, laser cutting, or CNC machining—technologies that would not be developed for at least another half-century—it was an extraordinary feat.

Over the past nine decades, technology has enabled improvements in materials, gear design, and production techniques, yet the calibre’s dimensions and architecture remain unchanged. Comprising 98 parts—each requiring custom manufacture and adjustment due to its minuscule size—the current version of Calibre 101 represents the fifth generation.

Working in a specialized workshop dedicated to this calibre, only a handful of watchmakers have mastered the skills required to assemble movements on such a microscopic scale. It demands dexterity, extreme precision, and great patience: assembling the 98 components takes 40 hours, and consequently, production is limited to just a few dozen pieces per year.

The new 101 Secrets watch faithfully adheres to the classic codes of High Jewelry: its double-row *rivière* bracelet is crafted from 18k rose gold and set with 124 pink sapphires (approximately 16.39 carats) graduated in size and color—ranging from intense cyclamen to a subtle pink hue—spanning 10 sizes and 7 shades.

Separated by a contrasting band of grain-set white diamonds, the two rows of gemstones are prong-set to maximize the light passing through them, thereby amplifying their color and brilliance.

The sides of the case are also grain-set with sapphires and diamonds, with the latter extending along the entire length of the bracelet. When revealed, the time is displayed on a shimmering white mother-of-pearl dial framed by a rectangular, diamond-set 18k rose gold bezel, bringing the total to 904 brilliant-cut diamonds (approximately 13.26 carats). This gem-setting masterpiece, crafted in the *Métiers Rares* workshop at the heart of the Jaeger-LeCoultre Manufacture, required 163 hours to complete.