With flat polished bases
I've seen these with wfs labels.
I believe even wfs collectors have difficulty telling Caithness ones from wfs, (I offered to include a few in the wfs collection I gave to the mould fund but
these bits were turned down because of uncertainty) but I'm pretty sure the wfs ones do not ever have the concave rounded base the Caithness ones do.
So perhaps the maxim is; rounded base = Caithness; flat polished base = unidentifyable
And neodynum ones are Caithness.