But let’s be a bit more specific. What gives gemstones colors, or rather, what changes the way they absorb and reflect light so that they come out in so many different, striking colors?

In September a cushion-shaped 5.44-carat Paraiba tourmaline ring flew past its US$60,000 upper estimate in auction at Bonhams New York to sell for US$533,900. This is bidding territory more ...