Thread A uses two strands together: knitting crochet cotton (4-ply, slightly twisted, beige) with crochet cotton size 10, white with 3.5 mm hook. Thread B is size 5 pearl cotton in rust, used with 2.0 mm hook.

Pattern 4 in Decorative Crochet.
Pattern 9, Cocktail, in 1000 Mailles.