I am often asked about the beads used for my card embroidery patterns on the Stitching Cards web site. I like to use silver lined glass beads because they give a jewel like effect when they reflect the light. The small round beads are usually referred to as seed beads. The beads are 2mm in diameter or 1/8 inch or aught size 10/0 (ten-aught). Various bead sellers uses different measurements when describing the beads so I have given the three most popular.
Originally aught size 10/0 meant there were 10 beads to an inch. With modern technology and machine cutting, there tends to be closer to 16 beads per inch. To complicate matters further Japanese beads tend to be a little larger than Czech beads of a given size number. If the beads are coated this can also add to the actual size of a bead.
The patterns are designed to accommodate slightly larger beads if necessary. If you have a row of beads that do not fit the pattern you could vary the number of beads to make them fit. I would recommend purchasing a small quantity of beads to start with to test the size. Shops often have packs of mixed colours in their range.
I get my beads from Creative BeadCraft. The link to small glass embroidery beads is: