I was working on a project where the client noticed that the right quotes were not showing up. Instead of appearing as a right double quote in dark gray, they almost seemed a white single quote.

At first, I thought that the text must be wrong or contain a strange character. But this was not the case. I started experimenting by changing the font to Arial and the quote appeared. I then went back the Google Font Crimson Text I started with and the right quote disappeared again. My next test was to change the font weight from 600 to 500 and the right quote re-appeared. I decided to check this out in Google itself and discovered the same issue :

Crimson Text Rendering Error

The right double quote problem appears to be a rendering issue with Crimson Text at semi-bold or 600 font weight. I sent this information to Google as part of the font feedback so it will be interesting to see if it gets addressed.