The price of stone bollards is primarily driven by the type of natural stone used. Granite is the most common choice due to its high compressive strength and weather resistance. You should specify the density (typically ≥2.6 g/cm³) and water absorption rate (ideally <0.5%) to ensure longevity. Basalt or Marble options may carry a premium price but offer different aesthetic finishes. Always confirm if the price includes surface treatments like polished, honed, flamed, or bush-hammered finishes, as these significantly impact both cost and slip resistance.