White-Point Star

A White Point Star Diamond was a diamond that was found only on the planet Gallifrey. The Time Lords, whilst being Time-locked in the Last Great Time War, sought a means to escape their imprisonment and thus their destruction. This led to Lord President Rassilon using The Master as a means of escaping into the universe. However, whilst the link was present in his mind, there was no physical link, which led to Rassilon sending a White Point Diamond through the time-lock, which the Master recovered and used as a means of bringing both the Time Lords and Gallifrey into the universe once more. It was destroyed by the Doctor with Wilfred Mott's gun. (DW: The End of Time)