Blind test: Counts of growth-rings on the five samples (L8, AT, E2, E3 and T) per expert.

Experts 1–6 are internal from the Swiss Federal Research Institute WSL, experts 7–10 from four external laboratories: the Laboratory for Wood Biology and Xylarium at the Royal Museum for Central Africa, Tervuren, Belgium; the Wood Anatomy Laboratory, University of Haifa, Oranim, Israel; and two anonymous laboratories (one European and one North American). Some of the experts counted along one radius, some of them along two or three radii of the wood samples. N means that no age determination was possible.