It was Pliny who provided the longest and most detailed description of MURRINA VASA: Their size never exceeds that of a small table, and, in thickness, they rarely are so thick as the drinking cups mentioned above. Their brightness has no intensity, they are shiny rather than brilliant. But what is really valuable is the variety of colours, since their veins repeatedly turn purple, to snow-white and a third shade between the two, just as when the purple gets inflamed in a change of colour or the milk-white goes red. Some people appreciate above all their outlines and certain reflections in the colours, like those observed in the rainbow. Other people, on the other hand, like thicker veins - any transparency or lack of colour is considered an imperfection - as well as grains and warts that, just as in the human body, are not prominent, but are mostly flat. A certain worth can also ascribed to their smell. -(Naturalis Historia 37.21-2)