I'd have to think the 2300-2400 F destroying the impurities is the reason that one crumbles. It was full of impurities. The normal treatment for ruby is 1800 C; 3200-3300 F. That's "way above" what you did. And it doesn't make "normal" rubies crumble. (if you went to 2400 C, you went way to hot, and that would possibly be why it fell apart as well...)
It is very interesting that we can make synthetic rubies and sapphires for industry from powders of alumina oxide and chromium oxide, sapphires only need the alumina oxide powder.
Give minimum not above 1000 degree and 5 minute and give sudden cool use water and after this process several time you got good result 👍 every time you saw improvement the stones 👍
I'm pretty sure a lot of corundum is dyed, so not only the red color disappears, but more of the fluorescent areas are exposed since the dye cooked off.
I think what went wrong here is that you overcooked them. I've seen it mentioned in papers before, but if you overheat a gem while treating it you can destroy it, causing it to lessen or even lose it's color and become unstable, just like the rubies here did. perhaps you might have more success treating higher quality corundum's? buying some sapphire gravel from gem mountain might provide a good amount of stones to test on. they usually have a lot bigger of a reaction to treatment :D
UV sounds simple but, there a wide range in UV type light so, more importantly, what is the nm frequency of your light? I suggest using 365nm but maybe rubies are better under a different wave length?
Would it help to put a bit of paper in the crucible and maybe put a lid on it to try and pull the oxygen out? It seemed like maybe the material in the cracks oxidized and swelled.
Good day, you know, I would like to see if a hexagonal Ruby looks good already cut and polished. I ask you this question because I don't know where there is a business like this here and I want to bring my own that I have. They are transparent for more than 400 carats and others for less carats. but although these occur. They would be good like Fura Star Ruby
