A shade is an item, not a note on an item
Each colour, finish and pack size you stock is its own item on the item master, with its own code, category, brand and unit. Emulsion · Brilliant White · 18L is one item; the same colour in 4L is another; the same colour in silk is another again.
That is what makes stock, valuation and reorder level work per shade rather than per product family. Worth being straight about the trade-off: colour and finish live inside the item’s code and naming, not as separate structured fields you can filter on independently, so a consistent naming order is worth deciding on day one.