But, taking the measurement for centimeters, about 5 cm is about 2 inches, so it's much too large for a ring. Napkin ring? Pat L.
But it's flattened and the measurement includes the little extension with the loop.
Seems small for a napkin ring.
If you take the loop and flattening into account might not be too big for a ring. The outer circumference of my wedding ring is just over 7cm, while the
diameter is just over 2 cms.
Flatten it out and add a loop and you might be close to 5 cm.
Pendant maybe? Is the loop a place for a chain?