The ammolite industry has not yet created an official grading system, but most systems refer to colour and brilliance. We use the following chart:
GRADE
DESCRIPTION
AA
This is the highest grade displaying 3 or more sharp and brilliant colours and/or a very unique colour pattern. Good colour change of flash when the stone is rotated. Iridescence : Brilliant multidirectional fire.
A+
Two or more distinct colours or play of colours. Good colour in low light. May contain minor inclusions (will not detract from the beauty of the gemstone). Iridescence : Bright.
A
Two or more distinct colours(usually orange, green) or play of colours. May contain minor inclusions. Iridescence : Bright/Included.
A-
Standard Grade. Colours are slightly less distinct and may show directional colour. May contain some inclusions. Iridescence : Included.
B
Faint less distinct colours. May contain some inclusions. Iridescence : Dull / Dark
Iridescence : Light effect causing a mineral to display a play of colors on an apparently monocoloured surface.
