core saturation

I have a Toroidal inductor core (from an old circuit) (OD-25mm, ID-14mm, H-11mm, color-Gray). inductance measured for different turns are as follows (T-L) "2 - 0.01mH 3 - 0.04mH 4 - 0.09mH 5 - 0.15mH 6 - 0.21mH 7 - 0.29mH 8 - 0.38mH 9 - 0.49mH 10 - 0.6mH 11 - 0.73mH 12 - 0.86mH 13 - 0.98mH 14 -...