There are 151.25 carats of rubies in total, each custom cut to fit the composition, mostly in oval and round shapes. It took several years for the jewelers at Van Cleef & Arpels to collect the 155 perfectly color-matched rubies used to create this unique piece, and another year to make it. It is a unique piece that took 2,050 hours of work. The movement, the Cartier-made tourbillon Caliber 9463 MC, is suspended between sapphire crystals. It is removable – but why would you remove it? Fine sapphires are also used to form the tips of the butterfly wings, between rows of diamonds that radiate from the center.

The star of the show is a spectacular 25.93-carat Sri-Lankan sapphire hanging from the bottom, chandelier style. The Tourbillon Mysterieux Azure Pendant watch combines high jewelry, high watchmaking and mystery-watch technology, all Cartier specialties, in a beautiful piece that is both wearable and collectible. Top watch brands, mindful of this, use emerald, ruby and sapphire in their most important jewelry watches, as the big three below demonstrate – from Cartier, Backes & Strauss and Van Cleef & Arpels. That is the reason Art Deco jewelry – heavy on the big three – is usually prized over other period jewelry. There are some rare finds among the so-called semi-precious gems that can be priced higher than the big three, but in general, a fine ruby, sapphire or emerald will hold its value and command more respect and a higher price than other gemstone. Sapphires are extremely hard and durable, so they will last a forever in a piece of jewelry, and rubies and emeralds are extremely rare.

The precious categorization is a reference to value: a really fine ruby, emerald or sapphire can be priced higher per carat than a diamond.

Everything else was called semi-precious. Until recently, only emerald, ruby and sapphire were officially called precious gems.

Ruby v sapphire