Upmarket jeweller Mappin & Webb – which sells diamond rings costing more than £20,000 – will open a new flagship emporium in Buchanan Street this autumn.

The news came as another shop favoured by celebrities also announced plans to move into the Buchanan Galleries.

Kylie Minogue and Sienna Miller are known to be fans of Greek beauty brand Korres which will open in the centre next month.

The new Mappin & Webb store, at the entrance to Glasgow's famous jewellery strip the Argyll Arcade, is much bigger than the firm's existing shop at 59 Buchanan Street and even features a grand marble staircase.

The unit, which will have more than 3000sq ft of retail space, used to be occupied by clothes store Ice and for a short time by Lush. But for many it will always be remembered as the Glasgow outlet of Bally shoes.

The lease on the shop, which is due to open in October, will cost the company £335,000 a year.

Stuart Moncur of property agents Cushman and Wakefield, insisted Buchanan Street was the place to be. He said: "The fact that the company chose Glasgow is testament to the continuing popularity of Buchanan Street as Scotland's most desirable shopping destination."

Meanwhile, celebrity beauty outfit Korres is set to open a swanky flagship store – its first ever shop outside London.

Korres, which uses herbal and traditional Greek ingredients in its products, has taken over the unit formerly filled by kids' clothes shop Gymboree.

The redesigned store, which promises to be a "little piece of Greece", opens on June 20 and will sell a full range of skin and hair products for both women and men.

Founder George Korres said he was excited to be opening a branch in Scotland's biggest city. He said: "We are honoured to be bringing our concept to Glasgow. A second UK store has been at the back of our minds for some time and Glasgow, with its buzzing pace and fantastically knowledgeable shoppers, is the perfect fit."