If you go to a lapidary supply store you can buy Diamond Trim Saw Oil.

This stuff is great for nenewing the appearance of decayed glass.

You can rub it on sparringly with your fingertip. Or pur a small amount into a container, and submerge the bead(s) into it. Check overnight. Leave it in for longer is you want to. Blot the bead(s) and allow them to air dry.

I use walnut oil on wood and seeds, It's very good for that. It is terrible for minerals.

For amber I recommend canola oil. (I kid you not.) This is what they used in Germany 100 years ago—because it has the same general specific gravity as Baltic amber, and absorbs well.

Take care. Jamey