How did he put such a gradient on the saw in Photoshop?

Question

Adobe Photoshop

Here I am trying to make a layout.
I can’t understand how he applied such a gradient to the iron part of the saw and made its color different?
Firstly, it is so difficult to single it out exactly, because there are many small fuzzy teeth inside.
Here it was originally black:

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Then he applied this gradient and changed the color:

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I selected it with the "Quick Selection" tool. layer for this selection. And got nothing. This looks ugly.
Thanks

Answer 1

Here is your "special" gradient. Just copied from the picture.

Answer 2

The answer to this question, as well as to ten subsequent ones, was taken and done.
There are no magic two buttons that you can press and get the perfect result. Try the "straight hand" selection method - it has never let me down personally. Automatic selection, at least, can be narrowed and expanded, cleaning up problem areas.