So I went through some old boxes on the weekend and discovered a bottle of Montblanc ink in with papers. No box, just the bottle marked with the little blue dot.
I know it was purchased in the early-mid 1990s as the papers it was stored with date it to that period.
Expecting it to be royal blue, I inked it up. Goes down blue black. Odd, I thought. Perhaps it is just the effect of the passing years. I certainly don't remember buying a blue black, but perhaps that is why I put it away and forgot about it.
Intrigued, I dropped some water on it. Nothing! Rubbing the page dry after 3 minutes and there was some barely perceptible shift around the 'k' in Miwok, otherwise completely colour fast.
So this means I have a 3/4 full bottle of the original MB Iron Gall ink?