I have a bunch of info about this stuff on my website
www.aandsopals.com in the learn opal drop down because we feel that the more we educate the public on this long forgotten gem is what will help bring it back around. Opal was once one of the most highly coveted and sought after gems for thousands of years before the technology to cut diamonds was even invented. This is a clipping from my website about the opal in question.
According to further writings by Pliny, the Roman senator Nonius once owned a grand opal, the most beautiful in Rome, said to be the size of a hazelnut, that Mark Antony dearly wished to buy as a gift for his lover, Cleopatra. Antony offered the modern day equivalent of a quarter million dollars for the gemstone. Nonius, liking neither Antony nor the deal, however, refused, and a furious Antony ordered Nonius’s execution as revenge. Nonius fled Rome before that command could be carried out, leaving all of his possessions behind, with the sole exception of the opal that had caused him such strife.