The problem seems to be that you're saving as .jpg, which introduces a lot of colours during compression. In the future use .png instead.
As for the ring itself, last update is certainly an improvement.
I'm not fond of the darker pixel on the outer edge. I assume they're there to make the edge stand out against the white background. I suggest working on a grey canvas.
Also, you should make the large gem either darker or brighter, as it blends in with the rest of the ring right now.