Kirin Tor rings

The Kirin Tor rings are a number of rings, all of which share the ability to teleport the wearer to Dalaran. Acquiring one of these rings is the requirement for the achievement.

These rings are all upgradeable: You buy the next better ring by tendering the current ring and a sum of gold. The amount of gold required depends on your reputation with the Kirin Tor faction, with the minimum cost being available at reputation.

Thus, an Inscribed ring can cost a total of between 7800 and 9750 gold, an Etched between 8800 and 11,000, and so on.