Sotheby's presents precious stones and jewels ahead of auction Sotheby’s will be offering several jewels from the Dimitri Mavrommatis collection as part of its Magnificent Jewels and Important Watches auction on November 12 in Geneva. The collection includes precious stones and avant-garde jewelry designs led by the "Graff Ruby,” which is estimated to fetch 6.9 million to nearly 9.2 million US Dollars. IMAGES AND SOUNDBITES