An antique necklace with a spider resting on a web at its center. Glowing green orbs of uranium glass are spaced out along the chain.
Uranium glass (aka vaseline glass) is a material more common to decorative glassware than jewelry, that fluoresces a strange neon green in daylight-- owing to trace amounts of uranium in the glass. It is generally negligibly radioactive and considered harmless.
*Note that the chain is white metal, which frequently contains nickel and can be irritating to those with metal allergies.