A jewelled gesso panel created by Margaret Macdonald Mackintosh was sold at auction yesterday for £1.7m.

The White Rose and The Red Rose, pictured left, was expected to attract bids of up to £300,000 at Christie's in London but sold for almost six times that.

Its fellow creation, The Heart of The Rose, was sold for £480,000. Both pieces were made by Macdonald, the wife of Charles Rennie Mackintosh, for the 1902 International Exhibition of Modern Decorative Art in Turin, and since then have been in the hands of private collectors, mainly in the US. Both measure roughly a metre square.

The panels represent the pinnacle of the artist's work and were selected by Fra Newbery, head of Glasgow School of Art, for the show. They had been on show at the Glasgow Art Club before the Christie's sale.

The White Rose and The Red Rose is a duplicate of a more elaborate version designed for an overmantle in the Mackintosh's own home in Southpark Avenue, Glasgow, with The Heart of The Rose a variant of a panel installed over a fireplace the artist designed for a Mr Wylie Hill for his home in Lilybank Terrace, Glasgow, in 1901.

Gesso is a medium created by mixing Plaster of Paris, rabbit-skin glue, whiting and water - and featured in the exhibition's Rose Boudoir. The works were described as "incredible, the best of the best" by Joy McCall, the specialist head of 20th century decorative art and design at Christie's.