Pliny the Elder, Natural History 37.81-82
In the course of discussing opals, Pliny mentions Catullus 52.
magnitudo abellanam nucem aequat, insignis etiam apud nos historia, siquidem exstat hodieque huius generis gemma, propter quam ab Antonio proscriptus est Nonius senator, filius Strumae Noni eius, quem Catullus poeta in sella curuli visum indigne tulit, avusque Servili Noniani, quem consulem vidimus. ille proscriptus fugiens hunc e fortunis omnibus anulum abstulit secum. certum est sestertio vicies tum aestimatum, sed mira Antoni feritas atque luxuria propter gemmam proscribentis, nec minus Noni contumacia proscriptionem suam amantis, cum etiam ferae abrosa parte corporis, propter quam periclitari se sciant, et relicta redimere se credantur.
The opal’s size is the same as a hazelnut’s, and there is a remarkable story we tell about it: there still exists today a gem of this kind, because of which the senator Nonius was proscribed by Antony – this man was the son of that Nonius Struma whom the poet Catullus was indignant at seeing in the curule chair, and was the grandfather of Servilius Nonianus, whom we have seen as consul. On being proscribed, Nonius fled, taking with him, out of all his fortune, just this ring. It is certain that, at that time, it was valued at two million sesterces, but how amazingly cruel and luxurious was Antony that he should proscribe a man for the sake of a gem! And no less amazing was Nonius’ obstinacy – to love the cause of his own proscription – especially since wild beasts are believed to tear off a part of their body which they know puts them in danger, and by leaving it behind set themselves free.