I always look for the fabric weight, so I would include that. Smart buyer will know that a heavier weight can be an indicator of quality, even for fabric like quilting cotton, and especially for fabric like velvet. I would also advise about sizing. Some less expensive fabrics are loaded with sizing, and after washing don't appear as nice.
You could say:
Quilting cotton by X MANUFACTURER weighs X OUNCES per yard and is sized/not sized. CARE INSTRUCTIONS etc...