[gmkcpa]

I encased the opal in 11mm heavy walled tubing, with no bubbles and put it into the kiln. Then I made my marble, puntyed up to the back, heated the heck out of the lens and pushed my encased opal into it - melted it in with no air bubbles, rounded it, annealed it and then examined it. Surrounding the opal is a circle about 1/2 inch in diameter, where I assume the glass holding the opal ends and the glass that I made the lens with begins.

How do I get rid of this ring?

For the first marble I did like this I used 15 year old tubing that I got from Wale (pyrex) to encase the opal, and the rest of the marble I made with Simax. I figured maybe the pyrex and Simax weren't compatible enough, so I encased another opal in Simax (using rods of Simax, which worked fine - no bubbles). I got the same result - a ring around the opal where it's glass encasing joined with the lens.

Any help available out there for me?