Review on Enhanced Burr Polishing Accessories for Engraving and Grinding by Sean Garrison

As you can see from the photos the thickness of the diamond coating on these bits is thin so durability is an issue for them. However, you can extend their lifespan by using them under slow-flowing water. In terms of functionality, I was able to easily grind softer stones like pastelite, limestone, etc. so they would be good for fossil carving and general softer stone shaping. I'm sure they will work well on harder stone too, but bit life will obviously decrease. If you need a full set of diamond coated Dremel bits to get you started and don't want to spend money on more professional bits then this is a good starter kit.