This beautiful Opal plan colour sock yarn is a navy shade or a very dark blue.  Perfect for men's hand knitted business socks.  
This yarn is 4ply.
The Opal brand is very well known for its very high quality yarn.  With 75% Virginia wool plus 25% of polyamid for lasting durability, elasticity, and for wicking away moisture.
Each ball contains 100gms/425m of yarn.
Recommended needles 2.5mm - 3.25mm.
Washine washable.  I pop my hand knitted socks into a laundry bag in the machine.  Pull back into shade, dry flat, and in the shade.