Chasing rainbows: The intense competition for colored diamondsSAN FRANCISCO – Sotheby’s in Geneva made auction history last month when it sold the Pink Star – a 59.60-carat oval cut pink diamond – for $83,187,381, a world auction record for any diamond (or gemstone or jewel, for that matter). Sotheby’s David Bennett called the stone “a true masterpiece of nature.” Four bidders competed […]