Chris Cwej's time ring

During his service to the Great Houses of the Superiors, Chris Cwej used a time ring.

Background
Soon after the death of Roz Forrester, the Seventh Doctor brought Cwej to Gallifrey for the first time; it was at this point that Cwej decided to stop travelling with the Doctor. When Cwej mentioned that he would like to visit Bernice Summerfield, President Romana offered to arrange a time ring for him. (PROSE: Lungbarrow) Soon Cwej was officially recruited by the House Military, and continued to serve the Houses throughout their War in Heaven, travelling to various locations throughout time and space. (PROSE: The Book of the War)

Notable uses
After the War, Cwej was experimentally transformed into a disembodied AI, housed in a virtual reality called the Vicinity, so that he could enter and control the bodies of other Cwejen. (PROSE: The V Cwejes) During this period, any Cwej-form he was controlling could summon his time ring and use it to travel. Cwej could also split the ring into multiple rings, which appeared at will in a shower of sparks as he flailed his hand; he could then fuse these back into the original. He divided the ring in two so that Larles and Kwol could use them to rescue human survivors from the devastated Earth of Dawn 1027; after two years, when their mission was accomplished, Cwej reclaimed the rings and rejoined them. (PROSE: A Bright White Crack)

Cwej noted that the time ring was "dodgy", but worked if he needed it to. After crash-landing on Marsogohso, a planet populated by descendants of a human colony, Cwej met Colette, a woman being pursued by a creature which repeatedly killed her in various timelines. Unwilling to use the ring around her for fear of causing paradoxes, he removed it and left it in a silver bowl, after which he felt unmoored from higher dimensions but more stable on his feet. Once they had defeated the creature, Colette stole the ring and used it to go back in time and become Kaetannan, a legendary interplanetary hero. Cwej realised that the amulet of Kaetannan, an ancient relic kept in the town and resembling a polished gold band on a chain, was actually his ring, and retrieved it. (PROSE: The Eternal)

When Cwej was unexpectedly sent to an unidentified Cwej-form on an uncharted desert world, he found that he was unable to summon his time ring. He speculated that this was because the Vicinity had glitched or been sabotaged, sending his consciousness to a point in space or time so distant it was outside its effective range. (PROSE: The Ursine Brood)

When Cwej was arrested for harbouring Larles and Kwol, the Superiors took his time ring. They gave it to Larles when she agreed to become one of their agents. (PROSE: The Aftermath)

Appearance
Cwej's time ring was normally gold in colour. By the time he had crashed on Marsogohso, the ring had a colour and texture like those of lead, gnarled and almost black with exposure. Colette polished it to a radiant gold when she assumed the role of Kaetannan. (PROSE: The Eternal)