May seem like an odd question, but I cant work it out. Trying to do a ring circle with color gradient from black to white from outer to inner of the circumference only. The normal radial tool will treat the ring as it is a circle and apply color accordingly. Not what I want. Just trying to grade the color across the rings own width.

There are a couple of ways, make a gradient, then crop out the center, however

First, do you know how to subtract from a selection? Make your initial elliptical selection in Replace (first icon) mode. Fix that by clicking inside. Put the tool into subtract mode (third icon) draw it in and fix (click in selection)

That gets an annular selection that you can fill. Please work on a new transparent layer, easy to correct, that is what they are for.

A black to white gradient will fill the selection. Tool options - gradient reversed - Blend color space linear - Shape radial. Draw it in from center of circle to edge of circle. In Gimp 2.10 there is a mid-point control for adjustment, but not enough for a clean white-to-black in the ring. see shot01.

Click on the gradient line to create a stop (splits the gradient) In the dialogue change Left/Right color to BG (which is white in this case). Adjust the positions of the stop, endpoint (black) and the centerpoint between the two to suit. see shot02

best of luck.

This is the worst Gimp forum ever, that recaptcha is plain stupid