The method of measuring long and round stingray skins is seen on the pictures above.
The average length of skin is:
about 2 times width for round shape
about 2.5 times width for long shape
The width is measured on the biggest 'star' of the skin (please note the white dots on the surface of the skins).
Row stone stingray skin
The method of measuring row stone stingray skins is seen on the picture above.