Crimp Beads
Crimp beads can be made of sterling silver, gold plated or gold filled, or base metal. Crimp beads are usually smaller than regular beads, but look very much like a 2-3mm round metal bead with a large hole.

Crimp beads can be used to detail or finish a project
Crimp beads are meant to be folded over 2+ strands of beading wire, and are strong but delicate. They are easily crushed if not care for properly. Crimp beads can be used to hold other beads in place on exposed wire, to finish a necklace or bracelet, or as tiny beads in a piece.
If you are finishing a piece, thread the crimp bead on your wire after all beads have been strung. Run the wire through the clasp and then back through the crimp bead. Ensure that the tail is also threaded through 1-2 additional beads. Pulling gently on the tail and holding the clasp securely, pull the crimp and other beads within 1mm of the clasp. The wire should move freely, but not be loose.
Close the crimp bead with a flat-nosed or crimping pliers. If you are using the flat-nosed pliers, gently flatten the crimp bead so that it will not move and the wire will not pull through it. If you are using the crimping pliers, use the larger crimp (nearer the handle) first, making the bead into a U shape. Turn the bead 1/4 turn, and use the smaller crimp (nearer the nose) to make the U shape into a round-shaped bead. Using the crimping pliers finishes the piece with a very professional look.
To use a crimp bead for holding other beads in place, string the crimp on the stringing material. Flatten or crimp the crimp bead immediately next to the bead you want to keep in place, add another crimp bead after the bead you want to keep in place and flatten or crimp it as well.
– L. Kvigne