These tools have some gnarly diamonds in a soft bond matrix. These guys will cut anyhing. These bits get it done. We love using the soft bond on quartz...it works great on all super hard materials. We recommed the Yellow Medium bond or the Orange Hybrid Bond for crunchy stones like Santa Cecilia Uba Tuba etc. The soft bond red bit will cut it fast, but the tool wont last as long as it should.
Recommed RPM 3500-5000
In our shop we generally run at 4500 RPM, remove .06 per pass at 60-70 ipm on quartz. This bit is engineereed for super hard materials like quartzites and porcelains....but we love cutting quartz with it. It's litterally our go-to bit.
Call Mark at 503-333-2485 if you have more questions.