Insane Stone Edge Hack A diamond cup wheel on an angle grinder smooths and shapes a stone edge with controlled passes. The result is a cleaner, more consistent finish with less manual sanding. This simple setup can speed up fabrication, reduce rework, and improve precision on stone projects, when used with safety gear. Tool: Angle Grinder with Diamond Cup Grinding Wheel Exact model: Not visible in the video. The yellow grinder appears to be a compact angle grinder, while the attachment appears Swipe or use ↑ ↓ to keep watching.