My latest artifact doesn't have much in the way of decorations, value, or even its name, but I still think it's awesome:
Arek Masos, "The Church of Talking", a cat bone floodgate.
This is a cat bone floodgate. All craftsdwarfship is of the highest quality. It is decorated with cat bone, Tower-cap and cave lobster shell. This object is adorned with hanging rings of Shell opal and menaces with spikes of cat bone, Tower-cap, Obsidian and Tiger iron. On the item is an image of Maples in Tower-cap.
Basic Value: 27600☼
When my bone carver when secretive, he wanted two stacks of bones and I only had a single stack of bones available (from a cat that was killed during an ambush), so an additional cat was butchered for the sake of this artifact.