On occasion, as most people who have nose studs have figured out at some point or another, you will need to conceal your nose piercing for long periods of time. If you were to simply remove the ring for a period of time the hole would quickly close back up. Even after a short period it could close back off enough that it would be extremely uncomfortable to put the ring back in. Worst of all, this could even lead to damage or infection. Therefor, the best way to conceal a nose piercing is to use a clear nose stud.
A lot of people who wear nose studs need to have them out for extended periods of time. It is often caused by something such as work or school. With this amount of time you need a high quality clear retainer. For the occasional use I would suggest the ones you might find at the mall in a store like Hot Topic. But if you need to use them daily-for work or school, these are very far from sufficient. You need to find something that will both hold up better and look a lot better. A higher quality clear retainer will keep your piercing significantly healthier as well.
If you are familiar with the person who gave you the piercing, and they are proffesional, then they should be one of the first people you consult because their advice will be a lot better than anyone elses. I cannot say for sure, but they will most likely suggest that you get one made out of a material like PTFE or, if you have a higher budget, one made out of quartz glass. These have a lot of advantages that the cheap ones will not even come close to offering. The main thing however, is that they stay in much easier and you will often not even notice you are waring them. The mall type clear nose stud have a horrible tenancy to constantly fall out because they have a poor shape and are made out of cheap plastic.
The type of clear nose stud retainer that you need to find are the ones which either have a corkscrew shaped protrusion at the end or one with an L shaped end. Most people find these to be the most comfortable and to stay in the best. However, there are a significant group of people who find them irritating to the skin or just obnoxious. Luckily, these people have another option. This is with a nosebone or pin style clear retainer. These are very simple-there is just a small bead with a strait stud coming off of one end. These are, of course, very similar to the ones you see in the mall. Obviously, you still need to find one of high quality if this is your preference. The last thing you want is a unhealthy piercing.
I cannot stress enough how important it is to find the clear retainer that works best for you. It cannot be a junk retainer from the mall or one that constantly irritates the skin around the piercing. You need to find a clear nose stud retainer of high quality. These will keep your piercing healthy and allow you to conceal it when you have to.