Purple is a soft violet color at cone 05/06, becomes blueish and lighter at cone 5/6 and become very light and blue at cone 10. A clear glaze will accentuate the color at cone 05/06 and 5/6 and cause more blue tones to appear at cone 10.
Tableware producers must test all finished ware to establish dinnerware status, due to possible variations in firing temperature and contamination.