I planted a cherry tomato new to me: Indigo Rose. It has lots of fruit that are nearly black in color about pingpong ball size but nothing is ripe. Fruit has been on the vine for weeks! According to what I Googled, the fruit is ripe when the very bottom is red. I’ve picked some with very little green left on the bottom and am trying to ripen on a windowsill. What is up with these tomatoes?
What a beautiful fruit! Looks like an eggplant, tastes like a tomato -- I love it. Since this is a new variety, in many ways you're breaking new ground. I think I would look at this season as something of an experiment, and just try the fruit to see how it tastes. As long as it's not getting rotten on the vine, though, you're good, I think..This article I found seems to have some interesting information: http://extension.oregonstate.edu/gardening/purple-tomato-debuts-%E2%80%98indigo-rose%E2%80%99