Wondrous item, rare (requires attunement)
You may use one of the pearls from this necklace to have advantage on a single death saving throw. If you have already failed two death saving throws, you can instead use five pearls to automatically stabilize yourself. The string starts with 49 pearls in total; each pearl is a luminescent off-white until it is used, at which point its color darkens to a glossy black. When all of the pearls have been used, the string becomes a mundane necklace of black pearls worth 150 gp.
If a pearl is removed from the string, it turns black and no longer has any magical properties. If the string is broken, all remaining pearls turn black and cease to retain any magic benefit.