Please check gauge below

Working with a F/5-3.75mm hook and 4ply cotton yarn work this sample
If yours comes out larger then go down a hook size, if it comes out smaller go up a hook size until it matches in size

Working in the round make a magic ring into magic ring
Rnd 1: ch 3 (counts as dc) 13 dc, join the a slst (14 dc)
Rnd 2: ch 4 (counts as dc, ch 1) dc, ch 1 in each st around, join with a slst (14 dc, 14 ch 1)
Rnd 3: ch 3 (counts as dc) 2 dc in ch 1 sp, dc in dc rep around 2 dc in last ch 1 sp, join with a slst (42 dc)

This should measure 5 ½ cm across