Signet was the focus of distinct attention from American jeweler, Zale.
Zale lost its number one slot in its home market last year to Signet, which has been growing fast in the US through its chains Kay and Jared.
Apax and Kohlberg Kravis Roberts are considering bidding for Signet.
The approach by Apax and KKR would probably lead to a management buyout of Signet, which could in turn trigger the company getting rid of the UK business.