Using Lilac cast on 32(40)44(48) sts and distribute them across four needles. The beginning of round is between needles IV and I. Work ribbing in the round for 8(9)10(11) cm.
110 cm/150 cm: work stockinette st as follows: 1 round Lilac, 1 round Frosty Night, 4 rounds Lilac, 2 rounds Frosty Night, 3 rounds Lilac, 3 rounds Frosty Night, 2 rounds Lilac, 4 rounds Frosty Night, 1 round Lilac. Use Frosty Night for the rest of the piece.
Women/men: work stockinette st as follows: 1 round Lilac, 1 round Frosty Night, 5 rounds Lilac, 2 rounds Frosty Night, 4 rounds Lilac, 3 rounds Frosty Night, 3 rounds Lilac, 4 rounds Frosty Night, 2 rounds Lilac, 5 rounds Frosty Night, 1 round Lilac. Use Frosty Night for the rest of the piece.
Note: When the you have worked stockinette st for 4,5(5,5)6(6,5) cm, mark the spot for the thumb: on needle II, work the first 1(2)3(3) sts, then work the next 5(6)7(7) sts using a different-coloured yarn. Move the marked sts back to the left-hand needle and continue working stockinette st using Frosty Night. Work until the piece measures approx. 11(14)15(16) cm from the ribbing or until the mitten covers your index finger.
Top decreases: at the beginning of needles I and III, k1, skp (= slip 1 knitwise, k1, pass slipped st over) and at the end of needles II and IV, k2tog, k1. Work the decreases on every round until 8 sts remain.
Break yarn, pull it through the sts and securely weave in.
Mirror left mitten, working the thumb hole on needle III.
Remove the scrap yarn. Using Frosty Night pick up and knit the sts from the top and bottom edges of the thumb opening and additional sts from the sides for 12(14)16(17) sts in total.
Divide the sts over three needles and work stockinette st in the round. When you have worked for 3,5(4,5)5(5,5) cm or the mitten covers half your thumbnail, work the top decreases: k2tog at the end of each needle until 4 sts remain. Then k1 and pass the other sts over from left to right. Securely weave in.
Steam the mittens lightly.