If you are spending money on duvet covers you want to make sure that you are getting well-made ones. A poorly made duvet cover is not going to look good for long and it will wear out much more quickly than one which may be more expensive but which is made out of much better materials.
There are a few key areas that tend to wear out more on duvet covers and these areas should be strong and free of problems in any new duvet. The areas that you need to be particularly aware of when you are shopping are the areas around zippers or openings, the seams themselves which run all the way around the duvet, and any areas where there is embroidery or embellishments on the covers you are looking at.
Duvet covers can close in one of several different ways. They may have a flap, a zipper or a row of buttons that hold the opening shut. This prevents the duvet from working its way out of the cover if you toss and turn in your sleep. If the duvet are fastened with buttons, you want to make sure that they move in and out of the buttonholes easily and that the buttons themselves are well attached.
In and of themselves buttons are not difficult to sew on if they fall off of the duvet cover. However you may find that if the buttons are not well sewn on this could mean that there are construction issues elsewhere on the duvet that might not be so easy to fix.
A zipper can be more of a problem to fix. You want to make sure that the zipper is sewn in well and that it is free of threads and cords which may get caught up in the mechanism. The zipper should be fairly heavy duty and able to withstand a lot of tugging and pulling. A zipper which is too lightweight will wear out overly quickly and this may mean you will need to replace it much sooner than you might want.
The seams and any trim need to be well sewn as well since they will also take a lot of wear and tear during the life of the duvet cover. You really don't want to have to sew seams if they become unravelled. At best it is time consuming and awkward to try and sew them and at worst, they may be impossible to repair leaving you with a duvet cover with holes in it.
If you check a duvet cover over before you purchase it, you can be confident that you will be able to pick one which has the quality you need and the look you want.