Pick up 2 size 15 beads, 1 Swarovski crystal, 7 seed beads, one half of the clasp, and 7 more seed beads.
Skip 12 seed beads and pass needle back through 2 seed beads, the Swarovski crystal and 2 seed beads. Stitch through the other centermost Tila bead hole, across the two Tila beads, and back through the hole you were exiting at the beginning of this step.
When adding the bar end of the toggle clasp, make sure that the loop is loose enough and large enough that the toggle can easily pass through the loop. You may have to add or remove beads as necessary.
Repeat the thread path twice more to secure, then weave back into the beadwork, tie a knot, weave in a bit more, and then trim your thread close to the beadwork.
Repeat for the other half of the clasp.