The ball gives a first impression
Review colour, structure, thickness and handfeel, then verify the labelled composition, weight and length. Photographs and descriptions help with shortlisting but cannot replace physical inspection.
The swatch answers project questions
Use the planned tools and stitch pattern. Record tool size, stitch and row gauge, dimensions and weight. Yarns of similar length or thickness can still differ in drape, recovery and stitch definition.
Evaluate after washing
Treat the swatch using the proposed care method, dry it fully and measure it again. Compare handfeel, surface appearance and colour. Agree production standards and any required tests for the intended use.
Move from swatch to finished project
Make a complete piece in a representative size and record actual consumption, steps and difficult details. Kit quantities must account for size, gauge and a reasonable allowance; one example cannot determine consumption for every customer.