The existance of these magical objects is one of the best kept secrets in the Elven Imperial Fleet; few beyond the Council of Admirals are aware of them. They were crafted millenia ago by powerful elven enchanters.
A Grand Teleporter is a large pearl, about the size of a man's head (they were taken from the giant oysters found on a few rare water worlds). Their surfaces are lightly etched with elven magical runes that can only be seen at certain angles.
A Grand Teleporter has the power to teleport large masses across vast distances.
When a person lays his hand on one and concentrates, he can see the area about him as if he was sitting on a helm. If the person then speaks the command word they can teleport themselves, the Grand Teleporter, and anything else the character wishes that is within a half-mile radius that they can see through the pearl. If the user wishes to be selective they can mentally "mark" an object while peering through the pearl, though this can take some time if they are marking a lot of objects. Anything so marked will be teleported. They can also simply choose everything to teleport everything withing range.
The Grand Teleporter can teleport up to 10,000 spatial tons of material. If the user tries to teleport too much, preference is given to objects closer to the pearl. The Teleporter will only teleport complete objects. You could not teleport a chunk of a planet into orbit, for example, nor could you use it to cut a ship in half. You could teleport a regular house, though.
Their are several ways to determine where to teleport. First, the user can specify an area he has been to before, and can visualize. Second, if the user knows astrogation coordinates, the Grand Teleporter understands those. Finally, the user can simply think of a distance and direction.
The Teleporter will not teleport objects into other objects. It will move any object the minimum distance required to keep the object out of another gravity plane. Thus you cannot teleport onto a planet or a ship. The pearl is "smart" enough to move only the objects required, not all of them. For example, if the pearl is used to teleport three ships, and one of them would end up in an asteroid, it will move just that ship so it appears right outside the asteroid's gravity plane.
The Grand Teleporter requires a vast amount of magical energy to function. It stores this energy within itself, and takes a full 2 months (60 days) to recharge after each use.
Because the ritual for enchanting Grand Teleporters is an ancient one, they do not have the built in feature of requiring an elf to operate the item like many of the more modern elven spelljamming items (i.e. the Crown of the Leviathan). Anyone who knows the command word can use it. This makes the elves extremely paranoid about the items, and will hunt down anyone who managed to obtain one.
The Grand Teleporter is found almost exlusively on the sphere bases of the Fleet. Since their incredible size makes it nearly impossible to move them wtih helms, the Teleporters are used to move the bases out of danger.