Photography about jewelry shooting skills, experienced friends to explain! thank you

This kind is usually made of a small white shed, and the lighting should be handled according to the actual items. Like the diamond ring in the picture, there should be a light on the top and a light on the bottom. If possible, add a ring flash in front of the camera, so it is not easy to drift. In addition, it is best to use a special crystal bracket to fix the ring when shooting. If the photos are taken well, the later stage is basically clipping and brightness adjustment. Personally, I like to use a pen to deduct a little, which is more convenient and can be deducted a little. There are many specific methods on the Internet, and I can do it myself. The black gradient of the background is OK by pulling it with the gradient tool in PS.

However, this is the first time I have seen a gradient of black and gray as the background.