You could simply ask how you make sure that no oxygen could enter, leave or react with the crystal. That's a simple and obvious question that nobody will fault

You could simply ask how you make sure that no oxygen could enter, leave or react with the crystal. That's a simple and obvious question that nobody will fault you for asking. There is a huge difference between that simple question and assuming they didn't make sure of that and the research has to be flawed or the researchers incompetent because of it. If there isn't a good answer to a simple genuine question, you can still go that step further and start questioning competency.