You may have heard this story in the last day or so: a tourist snapped off the toes of a 200-year-old Italian sculpture while sitting on it for a photograph. The museum is in Possagno, Italy, and specialises in the work of the 18th-century sculptor Antonio Canova.
The conservation and repair specialists could consider Opti-tec 5001 Optical Epoxy Adhesive or Opti-tec 5013 Optically Clear, Fast Cure Epoxy Adhesive. Both are epoxy adhesives with very high optical clarity, clear enough to make some invisible bonds and useful for the repair of relics and artifacts. Opti-tec 5001 has a very low viscosity for wicking into all those cracks, and Opti-tec 5013 is a medium viscosity, like honey, for gap filling challenges.
It might be a ticklish job.