Mrs. Homegrown here:

Note the lovely blue tinge of the garlic in my latest pickling adventure. Turns out that there’s a few reasons garlic might turn blue or green when prepared, but whatever the case, the coloring is harmless. What most likely happened here is that the garlic I used wasn’t fully dried, so it reacted with the vinegar in the pickling mix. I remember noting how moist the garlic cloves were as I worked with them that day.

If you want to read up more on this topic, and learn some of the science behind it (I’m too lazy to retype all the big words), check out this garlic fact sheet from What’s Cooking America. Scroll down to the bottom of the page.

By the way, the pickles I’m making are tourshi–Armenian pickles. If they work out, I’ll share the recipe.