This is a classic example of a mid-century glass bowl produced by Whitefriars Glass.
The thick, flattened bowl is made from sapphire blue-coloured glass encased in a thick layer of flint (clear) glass. Between these layers is a controlled bubble pattern that diminishes in size as it approaches the base. The underside of the base has a large central polished pontil. It is unmarked.
This piece has the pattern number 9099 and can be seen on page 15 of the 1957 Whitefriars catalogue. There were five sizes made in this range; this is the 6″ diameter version, which is the third biggest of the five produced.
It has a height of approximately 4.5cm and a diameter across the rim of about 15.2cm.
It has an unwrapped weight of 970g.
It is in good condition, with no chips or cracks, although there are a few minor scratches to the base and interior of the bowl commensurate with use.