Regarding diamond wheel test vitrify bond. Now we already test finished result is not ok. For chipping is ok but tool life less than cosmic wheel. Please see data test in attached file and data compare cost as below.
Cosmic 40,000THB/8,500 Corner = 4.706THB/Corner.
D&P 36,000THB/6,500 Corner = 5.538 THB/Corner.