This thin bronze ring, when worn on the smallest finger of the left hand, is purported to increase the potency of a vampire's blood.
The truth of its history and origins are lost to the passage of time, but it is rumored that a Ventrue had the ring created for him by a mortal magician. As the myth goes, the magician was something of a trickster, and like all things associated with 'the left-hand path', the ring is both a blessing and a curse.
What curse the ring might bestow has been the subject of many discussions; some say that when the sun shines, the ring leeches life out of any undead flesh it comes in contact with. Others say that the ring steals vitae as a vampire sleeps, leaving all but the most virile kindred empty husks before they can wake.
When worn appropriately, Juergen's band decreases a vampire's generation by one. All associated benefits - like a larger blood pool - are bestowed, and anyone diablerizing a vampire wearing the ring will reap the benefits of the lowered generation.
When the ring is in contact with any portion of a vampire's flesh other than the smallest finger on the left hand (which may vary from vampire to vampire), the character gains none of the advantages but still stands to suffer the true disadvantage.
This disadvantage is a reduction in the potency of a vampire's blood. If the sun rises and the ring is in direct contact with a vampire's skin, it will raise that vampire's generation permanently. This cannot be corrected by taking the ring off.
This disadvantage is cumulative; the vampire's generation will be raised each morning that the sun rises and the ring is touching their flesh. Removing the ring will halt the process, but will not reverse any damage already done.
When a vampire has done this often enough that they would be reduced to 16th generation, they crumble to dust. The blood becomes too thin and weak to support the deadened body any longer, and the vampire perishes.
A vampire who is savvy enough to use the ring each evening but remove it from their person before sunrise can enjoy a long, beneficial relationship with the artifact. Unfortunately, losses are usually incurred before the ring's true detriment is discovered.