The object appears as a small necklace made of platinum with a big, blood-red gem pendant attached to it. It feels cold to the touch no matter how much heat is applied to it. When investigated with a successful Arcana check, the item appears to be fused with a vague curse, evil spirit, or whatever nonsensical lie you can think of to make it seem untrustworthy. If it's sold, whatever shopkeeper it is sold to will refuse it as they assume it's plastic and you are trying to scam them, and any who realize it's real assume you are giving it away for free and give no compensation. The necklace is actually perfectly normal and not cursed... or is it??

"Oh no!! It's a cursed necklace!! If you put it on, surely you will DIE and/or become CURSED!! You should DEFINITELY put it on anyways for, uh, plot purposes..."