Miyuki seed beads are uniform in shape and size and are an industry standard for bead weaving  and bead embroidery.  Size 6/0 rounds are uniform in shape and size,  measuring 4x3mm.  The hole is 1.3mm mm, large enough for multiple passes of fine beading medium such as Nymo thread or Fireline.  There are approximately 12 beads per gram and 8 beads to a linear inch.