19 mai 2016
Lot 1273. Large and Impressive Tanzanite, Tanzania. Weighing approximately 92.60 carats and measuring 31.90 x 22.58 x 16.10mm. Sold for US$ 37,500 (€33,491). Photo: Bonhams. This fine oval-cut stone has an exceptional saturation of blue-violet. Both its luster and clarity are excellent. Most tanzanites typically commercially available in the market range in size from 1 to 3 carats and are pale in color. The present example is of a wearable size as an impressive pendant and displays an exemplary hue: a rich... [Lire la suite]
15 mai 2015
Merelani Mint Grossular Garnet, Tanzania. Estimate US$ 70,000 - 80,000 (€61,000 - 70,000). Photo Bonhams. A cousin to the deep green tsavorite is a young gemstone with a very long geological history--the Mint Grossular Garnet. Its home is the East-African bushland along the border between Kenya and Tanzania. The few mines lie in a uniquely beautiful landscape of arid grassland with bare, dry hills. No other occurrences of gem material have been discovered. Such stones rarely surface on the market-The color of this... [Lire la suite]
06 juin 2014
Rare alexandrite crystal, 41.11 cts from Tanzania.
29 août 2012
Tanzanite, Merelani Hills, Lelatema Mountain, Arusha, Tanzania.
13 novembre 2010
Gem-Quality East African Prase Opal. Mount Iyobo, Tanzania © 2002-2010 Bonhams 1793 Ltd Weighing approximately 28.35 carats and measuring 22.5 x 19.0 x 11.0mm - Sold for $3,050 Both chrysoprase and prase opal have been mined on Iyobo Mountain in central Tanzania for more than 20 years, with the first discoveries having been described by Dr. Edward Gübelin in 1975. Prase opal is a nickel-bearing variety of common opal, where nickel is the chromophore (the part of a molecule responsible for its color) that lends the neon... [Lire la suite]