Shadows of the Heart
Containing the memories of those long gone...
A memory orb is a gem that contains the memory of a single event. It can very in length from a few minutes to several hours. They are a variety of colors, usually a mixture of the gem itself and the color palette of the pony whose memory it contains. Memory orbs are usually perfectly polished spheres, though variants do exist.
In the Northern Empire, memory orbs are worth a considerable amount of caps. A memory orb that is at least an hour is worth 500 caps, with longer memories going for much higher prices.