  Conformal field theory predicts finite-size scaling amplitudes of correlation
lengths universally related to critical exponents on sphere-like, semi-finite
systems $S^{d-1}\times\mathbb{R}$ of arbitrary dimensionality $d$. Numerical
studies have up to now been unable to validate this result due to the
intricacies of lattice discretisation of such curved spaces. We present a
cluster-update Monte Carlo study of the Ising model on a three-dimensional
geometry using slightly irregular lattices that confirms the validity of a
linear amplitude-exponent relation to high precision.
