man, you forgot main rule - your first attempt refine should produce at least blue mat. If not - exit and start again. If you do - in 200 mats you will have from one to four yellow mats. Works like charm since beta
-vovus
I presume you actually needed one. The RNG AI detects your need and scrupulously avoids anything you don't already have.
The only way to get gold tempers is to have your inventory filled with them.