In a gilded ballroom at the Four Seasons hotel in Geneva last month, the world’s wealthiest collectors and their envoys gathered to bid on the final and most anticipated lot: a nearly 19-carat ...

Gemstones are treasured for their exquisite beauty, sentimental symbolism and—perhaps most importantly—their market value. These precious pieces of rare rock, once polished and cut, can be worth tens ...

Forbes contributors publish independent expert analyses and insights. Kate Matthams Spencer is a Paris-based writer who covers jewelry. Jewelry industry experts Joanna Hardy and Jessica Diamond have ...