I am looking for beads that have a 4mm-5mm hole to put the cord through. How do I determine what the hole size is?
Most of the large-hole beads have the hole measurement in the description of the bead. As an alternative, the pictures of the beads in the Fire Mountain Gems and Beads catalogs are actual size, unless otherwise stated on the page. With a sliding gauge you can measure the inside diameter of the hole on each bead to get close to the accurate diameter.
Once you have the diameter of the hole, you can then determine the diameter of the stringing material which is appropriate for that bead. In most cases, a bead with a 3mm or larger hole will accommodate the most commonly used cords and yarns. Make sure the hole measures just a bit larger than the diameter of your stringing material to ensure a good fit.