The next most popular question I get once they've purchased the glass is, how do I fit it??? Well this depends much on the watch brand. Some glasses are easy to replace, for example Rolex Submariner and Tudor Prince as all you have to do is remove the watch bezel and take out the glass from the front. The same can be said for a lot of Seiko models. This can be done by using a sharpe knife. However, some models require the movement to be removed, for example the classic Rado Diastar. I gave the following advice to a customer who asked me how to remove his Rado movement - "First unscrew the back, To remove the crown (winder) you must unscrew the locking screw which is located on the movement near where the crown is connected to the movement (some models have a push down button instead of a screw). Pull the crown and stem out and remove the movement, the glass can be pushed out from the inside. Reverse the steps to put the watch back together again." As you can tell from my brief description that this is not as easy as it seems and can lead to you creating more problems. My advice here is that if you’re not confident in removing the movement then take it to your local repairer.