Topics: Correct Powercord® Diameter with Swarovski crystal and Pearls
What weight of Powercord is best to use when making stretch bracelets using 6mm Swarovski crystals and 4mm glass pearls?
Both of those beads have a hole approximately 1mm in diameter, so your best option is the 0.8mm diameter Powercord. If you are choosing to knot the Powercord on the bracelets, don't forget to add a drop of G-S Hypo Tube Cement to keep the knot secure.
Please remember that Swarovski crystals have sharp edges that can, over time, wear through the cord and weaken it. You may find that a beading wire such as Accu-Flex® beading wire with a clasp is a better long term option.