During Louis XIV's reign, the Palace of Versailles would often experience time slips and somehow his silverware forks were imbued with the power to keep him and his court in the same time continuum.
The temporal effects of the Palace most likely caused the infamous Moberly-Jourdain incident of 1901, during which two women who were visiting the palace claimed to have experienced a time slip, and saw Marie Antoinette as well several other famous people of that time period.
There are twelve forks in total.
Protects its holder from temporal changes to the space-time continuum. For example, if a user goes back in time and prevents their parents from ever meeting each other then as long as they had one of these forks they wouldn't fade from existence.
If a fork being used to shield someone is neutralized, they are expelled from the current timeline and presumably erased from existence.
CollectionEditKept in Warehouse 13. Artie, Pete, Myka, Steve and Claudia used these to physically stay aware of their own timeline after Paracelsus changed history by traveling back in time.
Once the original timeline was restored, Artie discovered one missing out of the twelve. While Paracelsus was holding Artie prisoner in the alternate Warehouse 13, the alternate Benedict Valda was looking through Artie's Bag and took one of the forks. He didn't know what it was until after the time line was repaired and he wasn't erased like everything else. The alternate Valda remained in our universe until Pete snagged the fork he stole and neutralized it thereby erasing Valda from existence.
In "Endless", the memory Artie wanted to save in the Round Table was the time he snagged Thomas Wedgwood's Champagne Glass with his son, Scott Moore. While snagging the glass, Scott and Artie each carried a fork with them because at midnight the glass would reset time again to 11:35 PM, the exact time it was activated in 1941, and without the forks they'd both be trapped in 1941 forever. As long as they each had fork with them, when it was midnight and time reset again, they'd be popped out of the bubble and return to the normal flow of time.