I don't know if you already found your answer,
, but maybe I can help. I don't need the fg.
In his video, he explains that some people are getting like three transfigurations--especially the one where you get gem strength.
When you transfigure an item (after you masterwork it), it will say either "unmodifiable" or not. If it doesn't say "unmodifiable,' then you can transfigure AGAIN.
He explains that there is a 1/20 chance that you will be able to modify it again AFTER a transfiguration.
After you transfigure that, there is another chance you can get ANOTHER transfiguration if it didn't say "unmodifiable."
During these transfigurations, there is a small chance that the transfiguration will be gem strength. That is what most people want, but that is the part where it's purely RNG--we can't control whether you get this stat as a transfiguration.
I hope that helps.