The supermodel is rumoured to have accepted a marriage proposal from boyfriend Jamie Hince, 39.
Sources say she has treated herself to a diamond and platinum band from exclusive London jewellers Garrard.
'Kate is the main breadwinner in this relationship and has paid for her own ring,' a source tells Hollywood Rag.
'She went to Garrard and looked at its selection and a ring visitor went to her home to show her designs. She wants the wedding plans tied up by 1st May.'
The couple got engaged in Paris last month when Jamie got down on one knee in front of the Eiffel Tower.
Kate, 34, is said to want a summer wedding.