These rare vases are made of black amethyst, an unusual color for any European manufacturer. They are 9 1/2 inches tall and are found flared out as well as cupped in as shown here. An example, listed under the name Lady Cynthia, sold for $470 in 1999. Another sold for $1,000 in 2007. Two more sold in 2008 for $130 and $150. And in 2011, another black amethyst sold for $210.
At the left are two flared examples. John Atkinson of the UK, who owns them, sent me the photo in 2007.