Trivia question: What does my necklace have in common with astronomers, long-haul truckers, and steelworkers?

The Swarovski crystals in my necklace are made by the parent company of Swarovski Optik, makers of high-performance telescopes and binocular lenses. Swareflex produces those little reflectors on the freeway that mark the white lines at night. Tyrolit, a Swarovski subsidiary, makes precision grinding, cutting, and drilling tools used in heavy industry.