Idyrshuloi Crystals

Under the Laws of Life, beings cannot cross from the Quäena they were born in to other Quäenaï. However, in Kárydir during the First Age, a bubodan and an elf working together created the first idyrshulo crystal. Wearing it, the elf was able to travel to Irëduin. After he removed it, he was Expelled back to Kárydir. After he returned, he got to work on another idyrshulo crystal with his bubodan companion. This one, imbued with different magic, enabled travel to the Rift. Over many years, they perfected the design of crystals to take them to all of the Quäenaï, including one that allowed others to come to Kárydir.

Design

Each crystal was a different colour, symbolizing the colour of the Quäenaï they allowed travel to. The Rift was orange, Irëduin was blue, Kárydir was green, Earth was grey, Qarëya was yellow, Eldayen was red, and Erunor was black. The crystals were usually made into jewelry of some sort, like a pendant or bracelet.

Magic

The crystals allowed the wearer to travel through a cross-realm stargate to another Quäenaï, although one crystal was needed for each Quäena. If the crystal was removed while in the corresponding Quäena, the wearer was Expelled back to either their home realm, or, if they were wearing multiple crystals, to the realm they had visited most recently. The magic used to create the idyrshuloi was both highly advanced and highly secret; only the greatest mages knew how to make one.
The crystal did not actually have to be touching a person's skin for it to be effective, but rather some part of the whole jewelry piece had to be touching the person's skin.