French sizes
Yardage counted only for one strand (to allow knitting with alternative thicker yarn, using one strand only).
Material per size and #skeins:
Castel cuivre (copper) (50g/132m): 5,6,6,7,7
Midland brique (brick) (50g/103m): 7,8,8,9,9

Gauge, using 7mm needles, seed stitch:
10cm (4in)= 18 rows
20cm (8in)= 21 stitches