In crafting circles, rocaille is sometimes used as another term for seed bead -- any small, uniformly shaped bead. Some retailers and manufacturers reserve the term for a more specific type of seed bead with a square, silver-lined hole.
Seed Beads and Rocailles
Seed bead or rocaille -- whichever term you use -- refers to a tiny bead size ranging from, at largest, several millimeters across, down to beads smaller than 1 millimeter wide. These beads are generally made of glass and are used in weaving by needle or loom. Designs stitched into clothing, moccasins and accessories are often done with these diminutive beads. The color selection is vast for these beads.
Rocaille Shapes
While the terms rocaille and seed bead generally mean the same thing, the specifics may vary depending upon the bead manufacturer. The basic rocaille shape looks like a doughnut or ring. Some companies offer rocaille beads that have a square hole -- sometimes even lined in silver or another color -- but with the same basic outer doughnut shape. If you come across a project that calls for rocaille beads, any seed bead will do.