For comparison, here you can see how I worked the same shawl with Manos Del Uruguay Marina, a lace weight merino singles yarn (more photos and notes here):
Yarn: Cascade Yarns Heritage Silk (85% Superwash Merino Wool, 15% Mulberry Silk; 437 yards (400 meters)/100 grams): 5626 Turquoise, 2 skeins.
Needles: US size 5 (3.75 mm): 24″ or longer circular needle
Notions: Markers; US size F/5 (3.75 mm) crochet hook; tapestry needle.
Skill Level: Intermediate
Size: 50″ wide and 25 ½” deep at center back, relaxed after blocking.
Gauge: 22 sts and 33 rows = 4″ 10 cm in St st, relaxed after blocking.
Pattern available in I Like Knitting, August 2016.