Luxury jeweller Harry Winston has joined other leading design houses by launching a new website which allows customers to purchase jewellery, such as platinum engagement rings, online.

The jeweller, which has always referred to its stores as 'salons', is offering a small selection of its designs for sale online.

Most exclusive is the diamond and platinum Sunflower necklace, which weighs around 25.8 carats and features a diamond centre stone on each 'flower', set in platinum.

The Sunflower necklace costs $135,000, although most items on the site retail under $10,000.

Harry Winston has a reputation as jeweller to the stars, having made pieces such as a pink diamond engagement ring for Jennifer Lopez's wedding to Ben Affleck, according to jewellery expert Julie Shields.

Jennifer Garner and Paris Hilton have also been spotted wearing the designs for their nuptials and one of the most famous pieces ever, the 70-carat pear-shaped diamond ring given to Elizabeth Taylor by Richard Burton, was created by the designer.