According to one account, Jewel was the homeplanet of the Time Lords.
After the Second Doctor attracted the attention of the Time Lords so that they could deal with the War Lords, he was taken to Jewel and put on trial. The trial resulted in the Doctor being exiled to Earth. (TV: The War Games)
After the Third Doctor had been exiled on Earth for some time, Omega used a black hole to drain the power from the Time Lords' base on Jewel. The Time Lords were forced to assemble the first three incarnations of the Doctor together to stop Omega. After Omega was defeated and power was restored, the Time Lords lifted the Third Doctor's exile, (TV: The Three Doctors) but still kept watch of his TARDIS' time thread.
When the Daleks and Shazar stole the Fourth Doctor's TARDIS with plans to replicate it and take over the universe, the Time Lords became suspicious at its sudden disappearance and their inability to trace it. After some searching, the Time Lords found Shazar while he was gathering TARDIS materials and brought him back to Jewel. Under the Time Lord Council's demand, Shazar returned to the Daleks with cirenium that would sabotage their TARDISes. After the Daleks and their TARDIS fleet were destroyed, the Time Lords summoned Shazar back to Jewel along with the Fourth Doctor and Sarah Jane Smith. The Doctor and Sarah were then sent on a mission to deposit Shazar on a primitive planet where he couldn't do any harm. (COMIC: Return of the Daleks)
Behind the scenes
The planet Jewel sits in a peculiar position within Doctor Who continuity. When Return of the Daleks was published in 1975, the Doctor's homeplanet had appeared unnamed twice on television, but had been briefly mentioned as Gallifrey in 1973's The Time Warrior. Since The Deadly Assassin in 1976, the Doctor's homeplanet has been universally known as Gallifrey.
In the 2019 television series Good Omens, during the scene where Crowley considers fleeing to another planet, his Extremely Big Book of Astronomy includes a page on Gallifrey. The caption beneath it reads "Jewel, the Shining World". This title had not been used for Gallifrey in any previous story, but had originated in the infobox of Tardis Wiki's Gallifrey article, whose list of alternative names began "Jewel, the Shining World of the Seven Systems", concatenating titles given for the planet in the Return of the Daleks comic and The Sound of Drums.