The sharp edges or stringers around the holes of the beads are a normal result of the Venetian glass bead making process. Fine pieces of the glass remain on the mandrel that the bead maker uses to form the bead. They are not a defect or an imperfection, rather a sign that your bead is handmade.
Filing the sharp edges with a bead reamer will help prevent the beads from cutting your stringing material and allow them to sit flush to each other.
The bead reamer comes with a handle and three different tips; a large and small reaming tip for smoothing and enlarging holes and a 45 degree edging point for smoothing and rounding the edges around the holes. Lay a towel down to protect your work surface and have a glass or bowl of water handy.
Twist the handle to open the jaws or collet, insert the large reaming tip and tighten.
Wet the tip of the reamer and the bead. The water acts as a lubricant and prevents overheating which can cause the bead to crack and break.
Begin rotating and filing the inside of the bead hole. Do not put the reamer into the hole to the point where it becomes tight. This may cause the edges of the bead to chip or the bead to break. File until the bead hole feels smooth, rewetting the reamer and the bead from time to time.
Switch to the 45 degree edging point. Get the tip wet and carefully file any shards that remain on the outside of the hole. Do this until the edges around the hole are smooth and flush to the bead. Again be sure to rewet the reamer and bead from time to time. Be careful not to hit the surrounding surface with the reamer, it will scratch the surface of the bead.
By using the bead reamer, it will allow you to smooth out the sharp edges of the bead.