I write almost all of my letters these days with fountain pen ink. I regularly look at the various fountain pen/ink online stores to see if there is anything I would like. The answer is generally yes, but I refrain and restrain myself.
However, I am seriously considering the red inkvent calendar from Diamine. I have seen short reviews of the inks in it and I am rather impressed & taken by the colours. But, as you can see from the picture above, I bought the blue inkvent calendar in 2019 and still haven't tried out all the inks. Should I take the plunge? I cannot risk running out of ink, what would I use to write letters with then?