A Well of the FireGems is not a deep hole. In actuality, it is a stone altar.
Each Altar is two stides across and one stride tall. It is octagonal in shape, as the eight sided shape had a symbolic significance for the Order and the Dragons. Each side is covered with a large glyph surrounded by smaller ones in a language that is lost to the Mortal World. The top is covered with a pattern of similar glyphs. In the center of each Altar is a Fire Gem. It sits there waiting for its Worthy to come and remove it.
They are made of a light grey stone that is practically indestructable. There was said to be eight of them, but no one is sure. No one currently knows where any Wells are. Most of them are assumed lost or destroyed, as the Order’s temples were destroyed. There is a small temple in the Hinterlands, dedicated to a god of light, that is using a well as an Altar. The clergy of the diety are unaware of what they truly have, though they are aware that it has some connection to The Order.
Each Well creates a FireGem in the center of its top. That Gem is unremovable except by it’s Choosen Worthy. Once they touch it, it falls free, and they (or anyone) can pick it up. Soon after the FireGem is removed, another appears and awaits its next Choosen Worthy.
There is a ritual allowing a stone to be removed by someone else. That person is then compelled to find the Stone’s Worthy Choosen (and given an ability to roughly sense that person). That ritual is currently lost.
The Well can be used to communicate with Dragons and call them to the Well. Under extraordinary circumstances, the Well will teleport the Dragon from where ever they were in time and space to the Well.
Any Oath sworn while touching (or in proximity too) to the Well is binding. Those involved are compelled to abide by it. Thus the Order’s normal oath of fealty and honor are kept by the riders.