How do auction houses authenticate and value extremely rare diamonds?

Apr 8, 2025 ... This superb diamond is estimated in the region of US$20 million / CHF 18 million and will make its auction debut at #SothebysGeneva in the High ... ... rarest and most exceptional diamonds in the world. Fall brilliantly in ... diamond one of the most rare, valuable and beautiful in the world. EXPLORE. In this article, we examine three of the rarest diamonds worldwide and explain why they are so special. Sep 28, 2022 ... A rare deep earth diamond was unearthed from the Karowe mine. It was buried 660 kilometers beneath the surface of the Earth. Apr 9, 2025 ... A rare blue diamond was among the treasures on display at an exhibition of $100 million worth of the world's rarest diamonds in the United ... Apr 8, 2025 ... ABU DHABI, United Arab Emirates (AP) — A rare blue diamond was displayed Tuesday at an exhibition of $100 million worth of the world's rarest ... Feb 9, 2022 ... Experts predict that the supply of tanzanite could run out within the next 20-30 years, making this stone significantly rarer than diamonds. Sep 14, 2020 ... diamonds with the deepest origins — such as the famed Hope Diamond — are made of carbon from a separate source: a newly discovered, ancient ... Apr 8, 2025 ... “The largest red diamond in the world is 5.11 carats, and this is 5.05 carats,” says Redmayne. Red diamonds are so rare, he adds, that legendary ... Jan 17, 2018 ... The Koh-I-Noor is an oval-shaped diamond and weighs 105.6 carats. Steeped in mystery and legend, it is believed that the stone has been mined in India in the ...