|This article is about the current version of DF.|
Dwarves in strange moods will create legendary artifacts: unique, "named" items which are of unsurpassable quality (and often value as well). An artifact is the ultimate expression of a dwarf's desires, fears, memories and hopes in art form, and each dwarf will produce at most one in their lives (or die trying). Dwarves that create an artifact immediately gain enough experience to boost them to legendary level in the affected skill, unless they were possessed.
Dwarves drop artifacts in the workshop as soon as they are made. They cannot be traded, but most can be used just like any item of its type. A list of all artifacts in the fortress can be seen by pressing ( in version 0.40).
Artifacts are normally of extremely high value and quality, and can be used just like normal items of their type; they're therefore extremely useful in any situation where value or quality are important. Note that material and weight calculations still apply, so an artifact sword made of dingo bone or an artifact breast plate made of gold are not going to be overwhelmingly powerful.
Artifact furniture of high value can be placed in rooms to greatly increase the room's value (and hence quality), which can be useful to meet the room quality requirements of nobles. They can also be placed in high traffic areas of the fort, so that dwarves that pass by (or over) them will get happy thoughts from admiring them. Artifact mechanisms can be turned into levers and traps, which count as furniture.
Certain artifact types (barrels, buckets, mechanisms, etc.) can be used as components in some buildings; doing so will multiply the artifact's effect on fortress value.
Artifact equipment get a large ×3 quality bonus to their weapon accuracy and armor deflection values (compared to ×2 to masterwork); this is not enough to make totally inappropriate materials competitive with steel masterwork equipment. Also note that while they will be half again more accurate, artifact blades do not have a sharper edge than masterwork items of their material; in other words, their material type modifiers remain unchanged, and they will do no more damage than a regular item of their type (though they will never dull.)
 Finished Goods
An artifact gem is called a perfect gem and functions the same as a large gem, having all the same uses, i.e., none. However, unlike large gems, you can't trade artifact gems, and is therefore only useful for adding created wealth.
Artifact finished goods solely add to value of your fortress, or they can be traded in Adventurer Mode. A simple mod adds display cases to showcase otherwise unusable artifacts and increase your fortress's room values and displayed wealth. Display cases and pedestals are due to be implemented in the base game in the very near future.
Artifact cages and animal traps are unique in that they are capable of containing any type of vermin creature without them ever escaping - by comparison, certain types of vermin can gnaw, fly, or immolate their way out of ordinary cages depending on their materials.
 Adventure Mode
Artifacts can include books written by historical figures. Where they are stored is recorded during worldgen, and can be discovered in Legends mode.
 Other notes
Sometimes dwarves will grow particularly attached to weapons and armor, and if they become attached enough, they will name their armor/weapons. The armor/weapon will then be listed as an artifact, although its value and effectiveness will remain the same.
What causes dwarves to name their weapons is unknown - time alone will suffice (though it may take a very long time), but slaying an important historical figure such as a forgotten beast will often be enough. A weapon having a long kill list will also contribute to its naming. A weapon or piece of armor (even a shield) may be named if it only had a single kill.
After the weapon has been named, it will become fixedVerify to the dwarf that named it. It then becomes impossible to melt. If the dwarf dies, the weapon will be forbidden for use, until all dwarves that slayed something with that particular weapon (according to its kill list) at any given moment (before and after its naming) are properly buried in a coffin. If any of the slayers' bodies have been destroyed, the weapon cannot be used again.
Artifacts cannot be damaged by temperature extremes, building destroyers, or fire, although they will ignite and burn as is normal for their material type. They can be lost in pits, carried off the map by flows, stolen by thieves, atom-smashed by bridges, or melted by extreme heat. The loss of an artifact does not appear to affect the happiness of its creator.
In Dwarf Fortress Talk #7, toady stated that even when atom smashed, or melted by extreme heat (or destroyed in any other manner) The artifacts will not be deleted but instead receive a "Hidden" flag, which causes the item to respawn in a random location on the site in which it was destroyed perfectly unharmed after reclaiming a fort or visiting it in adventure mode.
After creation, an artifact cannot be further decorated (by encrusting it with gems, studding it with metal, or have images sewn into it). Your pitiful gabbro scepter cannot be made more valuable.
Artifacts disappear from the artifact list upon abandoning a fortress.
Artifact creation has a wider selection of possible item types for several skills, occasionally resulting in artifact items that could not be made normally, like bone shields or metal beds.
Artifacts can be disabled in d_init.txt
Artifacts created by happy dwarves (i.e. not fell or macabre moods) have a 1% chance to be named after the dwarf who created them.