Have you ever noticed how the most beautiful product photographs have this perfect, über-sharp focus from the very front to the very back of the product? I'll let you in on a little secret, they did not shoot it at f/32 (because of diffraction). In fact, what they almost certainly used is a technique called focus stacking.
The basic premise is simple, you shoot at the ideal aperture for your sensor and lens (generally f/8), move your focus point along the way of your subject (while snapping pictures at different focus points!) and combine the sharpest part of every image into one final shot.
It's actually quite easy to grasp and today I will show you how to make use of such a technique. While there are others way to do it, this will be the simplest.
The first step is to get your lighting correctly. Set your camera to the closest point that you want to focus on (this will ensure that you'll be cleared for the minimum focusing distance and that you will not have to recompose your shot later on). Then, get your lighting the way you want it and tweak the session settings until you get your desired look.
When you are ready to go with the focus stacking, take one picture and rate it with stars or colours in your photo manager (I use Capture One Pro). Move the focus point and repeat the process over and over until you have enough shots to cover every parts of the object you're photographing. One thing to be aware of is that (in order to make it easier for the stacking software) the camera must move as little as possible and the lighting needs to stay the same. There are two tricks to this, either you set a timer on your camera before taking the shot and you take your hands off it or you trigger the camera from your computer (⌘ + K in Capture One Pro on a Mac). Another thing to keep in mind is that you should pay special attention to important parts or features of the object. These need to be in focus.
Once the images are taken and rated, you need to export them somewhere. I suggest you to export them as TIFF without compression in order to retain the best quality. The next step is to open the bunch in Photoshop. You can do so by going to Scripts > Load Files into Stack and selecting the saved shots. After, you need to select the layers and head to Auto-Align in the Edit option in the top bar. The next and final step is to head to Auto-Blend layers and choose Stack Images. The resulting process can take a while and the results may not be perfect but I encourage you to try it anyway. If you want to go further, try exploring Helicon Focus. You could also try to manually draw masks for each individual layers.
I hope you found this technique useful and that you learned something. Do you have another way of doing focus stacking?