MIYUKI glass beads are considered a "world standard" for their high quality, brilliance, and uniform shape. They are highly sought after by fashion designers, artists and bead fans alike. 

These beads are sold in 24-28 gram 6" tubes. There are approximately 315 6/0 beads in a 6" tube. In some pattern books, they tell you to use an E-Bead, and this refers to both 6/0 and 5/0 seed beads.

Size 6/0 seed beads are 4mm in diameter.   Their hole size is 1.5mm.

In comparison to another Japanese brand called TOHO, both are of high quality.    Miyuki beads are more cylindrical; Toho more round.   As a result, Miyuki 6/0s are slightly different in size than Toho 6/0s.   TOHO have smaller holes.    TOHO finishes have a slightly more textured finish with more variations and often slightly more saturated in color.

Czech beads, in comparison, are much more irregular in size, more saucer like in shape, with much sharper holes and holes which vary a lot in size.    A third Japanese brand - Matsuno - is more similar to the Czech beads, though the holes are not as rough.

If you were making an ethnic looking piece with Czech seed beads, your piece would look hand-made.    If you were using Miyuki or Toho beads, your piece would look machine made.