In psychology, discriminant validity tests whether concepts or measurements that are not supposed to be related are actually unrelated.
A result greater than 0.70, however, suggests that the two constructs overlap greatly and they are likely measuring the same thing, and therefore, discriminant validity between them cannot be claimed.
Recommended approaches to test for discriminant validity on the construct level are AVE-SE comparisons (Fornell & Larcker, 1981; note: hereby the measurement error-adjusted inter-construct correlations derived from the CFA model should be used rather than raw correlations derived from the data.
[3][4] Voorhees et al. (2015) recommend combining both methods for covariance-based SEM with a HTMT cutoff of 0.85.
[4] A recommended approach to test for discriminant validity on the item level is exploratory factor analysis (EFA).