This ring was in need for a channel to be rebuilt. I was to only repair and rebuild the one channel on the sapphire/diamond band closest to the diamond band.

I first rolled a gold wire in the rolling mill to flatten it out.  I gave a sweeping arch to match the channel. 

I saw that it would be easier to unsolder the rings, so I could have better access to the side of the ring.  I tacked the new channel in place with the laser welder.

I then flowed solder across the entire top.

Here is the new channel shown after the initial sanding.

Instead of sanding out the wear-and-tear scratches from the shank, I burnished out the dings with a tungsten burnisher.

I polished and soldered the rings back together.

Now it really shows how worn the other channel is.  But it was a huge improvement.  The ring looks great.