Refine cost seems to now be:
20 diamonds to lock a stat
30 diamonds per refine stone (1 needed per refine attempt)
100 diamonds for every locked stat on every refine attempt
I locked one stat and the refine cost was 100 diamonds. I locked a 2nd stat and cost went to 200, I locked a 3rd stat and cost went to 300.
It does seem a ridiculously high cost for a random refine. Original poster spent 800 diamonds for just 2 refines. Why such a high cost?