Ye Olde Power Stealing Jewels

[Scrasamax]

I want to make a set of magic stealing jewelry, the proprietor of the jewelry sells it at a steep discount, but reaps a reward in the energy that the jewels harvest and return to him, the holder of the master jewel.

Life energy is cliche and won't last long, plus will draw all sorts of unpleasant PC attention.

I was thinking basically stealing mana/magic power/potential from those who wear it. Non magic users wouldn't notice a mana/energy drain since they are not attuned to it, but they would notice side effects of it's absents. Stuff like depression, lethargy, morose and morbid thoughts, or if an individual were more attuned to those darker energies they would be swing more towards the manic side of the pendulum.

What can I do to keep this from being cliche?

[valadaar]

Perhaps they draw upon the wearer's fortune and operate like a lottery terminal.

They constantly draw down the wear's luck, but occasionally return it to them in large spikes.  This return is only partial, so over the long run, their fortunes are reduced, but the occasional spike of good luck makes them feel lucky.

This takes advantage of the tendency to remember only the exceptions, and not the day to day haze of misfortune.

[Scrasamax]

Perhaps they draw upon the wearer's fortune and operate like a lottery terminal.

They constantly draw down the wear's luck, but occasionally return it to them in large spikes.  This return is only partial, so over the long run, their fortunes are reduced, but the occasional spike of good luck makes them feel lucky.

This takes advantage of the tendency to remember only the exceptions, and not the day to day haze of misfortune.

An interesting idea, but I was looking for something more along the lines of marginally or minimally affecting a large group of people to the advantage of a single person. I was looking at it as a power source for a low to mid level villain. A sorcerer (innate spell ability limited by power rather than memorization) but instead of having the usual compliment of spells, said magic user has the daily spell allotment of 20 0-level characters. While this doesn't let him cast high level spells, it would give him a stupendous pool of low level spells, and spells that would allow you to accumulate power could become very large, like powerful summoning spells, or area affect spells like weather control. The PCs would have to discover the cursed nature of the jewelry, remove it from the afflicted and then attack the villain.

[valadaar]

Well, of course that  a portion of luck that it did not return to the wearer is your payload streamed back to the creator of the item.  It just happens to arrive as manna instead of luck.