To assess the present state of agreement between labs worldwide, and to help improve this agreement, an international inter-laboratory exercise is required.
We propose to use the initial distribution of the 'age solutions' as an opportunity to carry out such an exercise in that we will distribute the solutions without revealing full details of the calibration results.
When the various laboratories receive the solutions they will only know what each solution is broadly analogous to (e.g. a young coral) therefore the exercise will be blind at the 'few percent level' which is more than sufficient as we are attempting to quantify agreement at the per mil level.
... watch this space.