28 Feb '17, 6pm
A Roman pale-green glass jar.
The age of the vessels, and where they are found, can also contribute to a richly coloured surface. ‘The glass can have what we call iridescence, where it has oxidised,’ says Delaloye. ‘It's a good sign that a piece may have been underground for almost 2,000 years before being discovered.’ In this video, Delaloye demonstrates how the condition of ancient glass is assessed using UV light, and explains how rare artist signatures can reveal details about the history of an object — as well as its value. ‘When you start collecting you get to know so much about the pieces you own,’ she adds. ‘It can become addictive.’