The colouring strength of the pure saffron is influenced by the proportion of red stigmas compared to the yellow or white parts of the flower (known as the style). More yellow or white parts imply greater floral waste and lower coloring strength. Therefore a high quality of pure saffron from India has a less yellow or white part attached to the bright red stamen.
As per ISO standard (IS 3632), the quality of saffron depends upon its grade, which is based on specifications of length, colouring capabilities, dryness and its other constituents. As per ISO standards saffron has been categorised into four grades. While Grade IV is the most inferior quality saffron, Grade I is considered to be pure and finest quality.
Following is the minimum standard measurement of grade - I saffron i.e., the finest quality saffron.
- Stigma fibre length 1,2-3.8 inches;
- Minimum colouring effect 230-250 +/LI;
- Moisture percentage (10-19 percent);
- Mineral materials (5-7 percent);
- Sugar (minimum);
- Fat (5-8 percent);
- Protein (12-14 percent)