Repairing broken stone sculptures requires adhesives that offer strength, durability, and minimal visibility. Here are the most effective options:

1. Epoxy Resin: A two-part adhesive known for its strong bond and resistance to moisture. Ideal for heavy or load-bearing stone pieces. Opt for clear or stone-colored variants to blend seamlessly.

2. Polyurethane Adhesive: Flexible and waterproof, polyurethane works well for outdoor sculptures exposed to weather. It expands slightly to fill gaps, ensuring a tight hold.

3. Stone-Specific Glues: Specialized adhesives like cyanoacrylate (super glue) or acrylic-based formulas are designed for porous materials like marble or limestone. They dry quickly and leave minimal residue.

4. Hydraulic Lime Mortar: For historical or antique sculptures, traditional lime mortar provides a reversible, non-invasive repair method while maintaining authenticity.

5. Polyester Resin: Often used with stone dust filler, it creates a durable, sandable bond for intricate repairs.

Tips for Success:

- Clean surfaces thoroughly before application.

- Clamp pieces firmly during curing.

- Test adhesives on inconspicuous areas first.

Choose the adhesive based on the sculpture’s material, location, and structural needs for a lasting restoration.