Sarah Ferguson's stunning engagement ring is one of the lesser-known pieces of jewelry in the Royal Family. But there's a special reason Prince Andrew chose a rare ruby diamond for his bride-to-be.

The auction totaled $49.2 million, with 97% of the 179 lots sold. At a Sotheby’s New York auction, a 10.33-carat Burmese ruby ring sold for $5.5 million, far surpassing pre-sale estimates. The event ...