Exotic substances like polonium and americium exhibit alpha radiation. While deadly poisonous if swallowed, these materials are safe to handle as the alpha radiation is unable to penetrate skin, or even a few centimetres of air. The radiation consists of "heavy" particles, much heavier than other kinds of radiation.
Many people fear ionizing radiation, or more specifically, fear the concept of radiation. It is the ultimate threat: a toxin which you cannot see, hear, or smell. Pedantry over different types of radiation is irrelevant. To the ignorant, the invisible enemy is everywhere.
The Alpha Pendant contains a significant amount of radioactive americium. Beyond the visceral thrill of carrying a vial of poison around your neck, the americium serves a purpose.
The pendant consists of an evacuated glass cylinder, set in gold. Within the glass is a wheel of metal foil, mounted on the finest of needle bearings against jewelled supports. Every effort has been made to minimize friction of the wheel's rotation. Attached to the wheel are four paddles, and to each paddle a small disk of americium is attached on one side.
The alpha radiation carries momentum. The asymmetry of the paddles maximizes the effect. The power delivered is minuscule, but balanced against the inertia of the foil, the precision bearings, and the high vacuum it resides in, the resulting force is enough to rotate the assembly once per second.
The outer circumference of the wheel is partially coated in reflective silver, the remainder in absorptive black nanocrystals of gold. The pattern of reflective/absorptive coating is such that the reflected light, visible through the glass window on the pendant, creates the characteristic double-thump of a human heartbeat.
In essence, the pendant is a nuclear-powered trinket, both simpler and more intricate than a watch.
The mechanical heartbeat of the Alpha Pendant pumps no blood, but its silent pulse is a visible beacon of hope, a reminder that if we put our minds to it, it is possible to make something that lasts. With a half-life of 432 years, the americium-powered heartbeat will outlive your great grandchildren.