Hi Gary, i have since been informed that these blades are part of Rubi's budget range and just to add the blade was not used under stress as it was a straight cut.
My take on it is!!!.. with these being on the low quality side to what Rubi top range is, the steel of the blade cannot take a lot of heat generated by dry cutting grade 5 porcs, yes the diamonds might cut great but if the body of the blade and also that the blade flange is thin then this contributes to blade warping and hence the break away just below the diamond segments each time of the 2 breakages i have had.
I have given the blades to rubi but as present have yet to hear anything back from Pat..