Cone ends are often used like bullet ends, to finish the ends of multistrand necklaces. For this reason, they are sometimes also known as necklace cones.
Cone ends are also popular for two styles of earrings -- shorter cone ends can be used like a bead cap, with dangles below like flower stamens. Longer narrow cone ends are often used for beaded earrings, fringe earrings, and liquid silver earrings.
The outside of the cone can be plain or decorative. The inside of the cone gives you a convenient place to hide knots and/or the transition from multiple strands, to just a single strand or wire. See bullet ends for an illustration of this type of transition.