Anyone grown sweet mambas?

Hi, I apologise if this is a really silly post, I've got sweet mamba peppers growing, I've got just one large non green fruit and it's been deep purple for a few weeks. I have read up on it and people say that they do change to red, but I'm concerned that I'll spoil it, is this normal, how long would it often take to change colour and is it possible that it's just supposed to be like this?

Thank you, and apologies again if dumb question.