This string of beads appears to be a hemp string with lustrous red beads of various sizes hanging from it. When activated, it briefly appears in its true form: a golden chain with golden spheres attached by fine threads.
Numerous varieties of the necklace of fireballs exist. This variety has one 6d6 sphere and two 4d6 spheres (DC 21). When all the beads are gone, the necklace becomes a non-magical hemp string.
Activate; 1 Action; Interact; Effect You detach a sphere from the necklace, causing it to glow with orange light. After you activate a sphere, if you or anyone else hurls it (an Interact action), it detonates as a fireball where it lands. Your toss can place the center of the fireball anywhere within 70 feet, though at the GM's discretion you might need to make an attack roll if the throw is unusually challenging. If no one hurls the sphere by the start of your next turn, it turns into a non-magical red bead.