Glas bowl made by the Edinburgh Crystal Glas Co Ltd. The glas is cut by hand using an industrial diamond cutter, an instrument like a tiny circular saw. This requires skill and precision, as it is the particular angles and edges of the cuts that makes the glas sparkle in the light. As the cutting leaves the glas roughened and dull, the shine is restored by acid which disolves away the scratched surface layer.
© Science Museum / Science & Society Picture Library