Rebel investors led by the UK Active Value Fund have already forced an emergency general meeting next month when shareholders will be asked to vote on plans for the break-up and sale of the group.
Yesterday the dissidents offered to waive £150m of dividend arrears in an offer that could be worth 20p a share to ordinary shareholders.
UK Active Value, led by Julian Treger, wants the company to seek valuations of Signet businesses including H Samuel and Ernest Jones. It offered ordinary shareholders 20p a share subject to the break-up value of the group exceeding £700m, plus 20 per cent of any proceeds in excess of £800m.
Mr Treger said: "Shareholders have a right to know the value of their businesses and this is the last offer we are prepared to make."
Signet chairman James McAdam said: "This is a transparent attempt by a small group of preference shareholders to justify what is now seen to be a seriously flawed resolution."
An analyst commented that Mr Treger was "looking at the world though rose-coloured spectacles".