One question I've seen asked here on Alcademics and on other websites is whether clear ice will turn cloudy when stored. The answer is no, it will not.
Ice is cloudy because of trapped air and impurities like minerals, along with any cracks that make it hard to see through. Once it's made, it pretty much stays as it is. It may absorb smells and sublimate/shrink if not kept in a closed container in the freezer, but that won't impact clarity.
If your ice starts out clear (from a machine or by using a form of directional freezing) it will remain so.
If you have a partially frozen ice cube that looks incredibly clear however, it will likely become cloudy when the center finally freezes. This is because the last part of ice to freeze is usually where trapped air and impurities are pushed.
To read all the ice posts here on Alcademics, check out the Index of Ice Experiments.