Buyers must prioritize the diamond concentration and grit size; a higher concentration typically ensures a longer lifespan and faster cutting in hard granite. The bond hardness is equally vital—soft bonds are required for hard granite to ensure new diamonds are exposed, while hard bonds are better for abrasive, softer stones. Additionally, verify the segment height (typically 10mm to 20mm) as it directly impacts the tool's longevity, and ensure the steel core is high-quality spring steel to prevent warping under high temperatures.