From: http://www.acmoore.com/premier-yarns-premier-home-cotton-...

Size I (5.5mm) hook

Use a gauge of 14 sc x 16 rows (about 4 inch) to crochet a mug jacket that measures about 3-1/2 inch in height and 7-1/2 inch at lower edge, 9-1/2 inch at upper edge and 12 inch at end of tab.

Ch 29.
Row 1: Sc in 2nd ch from hook and in each ch to end, turn – 28 sc.
Rows 2 and 3: Ch 1, sc in each sc across, turn.
Row 4: Ch 1, sc in first sc, sc 2 in next sc, sc in next 12 sc; rep from once, sc 2 in next sc, ch 13, turn.
Row 5: Ch 1, sc in 2nd ch from hook and in next 11 ch, sc in each sc across, turn – 43 sc.
Rows 6 and 7: Ch 1, sc in each sc across.
Row 8: Ch 1, sc in first sc, sc 2 in next sc, sc in next 13 sc; rep from once, sc 2 in next sc, sc in each sc to end, turn – 46 sc.
Row 9: Ch 1, sc in first 2 sc, ch 3, sk 3 sc, sc in next sc and in each sc to end, turn.
Row 10: Ch 1, sc in first 34 sc, turn.
Row 11: Ch 1, sc in each sc across, turn.
Row 12: Ch 1, sc in each sc across, turn.
Row 13: Ch 20 for button loop, sc in each sc across.
Fasten off.

Finishing: Fit jacket around mug and mark position for button. Sew button in place. Weave in ends