Text Box: We can custom fabricate almost any type of Natural Diamond Bit you can think of. Diamond sizes from grit size to 1 carat are available, although most common natural diamond drill bits for drilling simple abrasive sands will have 6-8 or 8-10 stones per carat (spc). We are now able to combine natural diamonds set in exposed ridges with diamond-impreg grit as a backup cutting structure in the blades as much as 3/8" deep.