Style: Glass fires the imagination: Four millennia of glass artistry are represented in a new museum collection. Jonathan Glancey was dazzled by it

No material, according to John Ruskin, the Victorian polymath and critic, 'is so adapted to giving free play to the imagination'. He was referring to glass, that fascinating medium which, when molten and syrupy, can be bent, blown and moulded into an infinite variety of shapes.

You can test the truth of Ruskin's claim next month by visiting the Victoria & Albert Museum's fascinating new Glass Gallery. Curator Oliver Watson and his team have assembled and displayed about 6,500 works from the second millennium BC to the present day. But the design of the gallery - by Penny Richards of Page + Richards: Architects - is itself a display of the contemporary glass artist's imagination and skill.

Danny Lane, best known for his furniture made from sheets of thick green glass, has created a dramatic, punky balustrade running up the glass stairs and along glass floor of the gallery's mezzanine. Composed of 140 glass pillars, which look like wobbly stacks of cassette boxes, it is a remarkable example of glass engineering.

Watson has not bowed to the modern convention of housing the barest few objects in each display case; he has crammed them as full as Ruskin did his cabinets of curiosities.

Light passing through the profusion of coloured, engraved, etched, turned and otherwise decorated glass creates a rainbow of delicate - and sometimes not so delicate - colours, that soften the gallery's chaste white walls. Refracted through glass, the light throws mesmerising patterns on the walls and floor, and the quiet, abstract explosion of colour animates the whole room.

The display is organised chronologically - which makes sense because the history of glass, if not linear, is clearly marked by key technological developments. For example, the earliest glass that the ancient Egyptians used was dense and opaque: it could easily be mistaken for marble.

Stone Age man had used natural glass (found where lightning strikes sand or where molten lava has been cooled by water) for arrow heads and cutting tools; but the Glass Gallery is not over-concerned with the archaeology of the substance. Its collection really gets going with the invention of Damascus glass, a mixture of silica and soda that the Mesopotamians turned into the clear material we have prized (and broken) ever since.

All early glass was blown, as in the tourist-pulling workshops of Murano, where it is still tortured into miniature giraffes and silly pink mice. But the key developments on the way to modern glass were the techniques of cutting, engraving, acid-etching, sand-blasting, sand-casting, enamelling, pressing and moulding. Even so, some of the greatest glass designs of recent times have been hand-blown: Joseph Paxton's Crystal Palace, the world's first hi-tech building, was glazed with 1 million square feet of blown glass.

The gallery houses examples, good and bad, of just about every type of glass you are likely to encounter. Watson is no slave to good taste: two of the most enjoyable pieces, displayed in a cabinet of their own, are glass busts of Victoria and Albert, original patrons of the V & A.

Much of the glass produced in Italy, Japan and Scandinavia in the past four decades has been overblown, and towards the end of its chronology the gallery does veer preciously close to uninhibited kitsch. My favourite modern piece is a sand-cast crocodile made by Amanda Brisbane. This sort of design could easily be mere whimsy in the wrong hands, but Brisbane has given it a snappy humour and creative bite.

Indeed, the descent of modern glass into kitsch was indirectly encouraged by Ruskin, who hated the abstract geometry of machine-made cut glass. Like William Morris, his disciple, he argued that the irregularity and unpredictability of blown glass was a sign of the craftsman's intellectual, moral and artistic freedom.

'All cut glass,' Ruskin thundered, 'is barbarous, for the cutting conceals its ductility and confuses it with crystal . . . The old Venice glass was muddy, inaccurate in all its forms, and clumsily cut, if at all. The old Venetian was justly proud of it.'

The most imaginative designers have blown glass ever since - but while this facilitates freedom of expression, it also encourages a lack of creative discipline. Perhaps this is why some of the ultra-modern and rigorously practical uses of glass - Pyrex glass-ceramics and glass-fibre - hold so much appeal.

The new V & A gallery, however, is a shrine to the decorative arts, and these heavy-duty industrial glasses have no place there.

They may be better made and ultimately more exquisite than art glass from Fifties Stockholm or Eighties Milan, but they seem simply too perfect for all those glass makers who have swallowed the Ruskin line.

The Glass Gallery, Victoria & Albert Museum, London, opens on 20 April.

(Photograph omitted)