Making diamonds in an oven


After reading various posts on here I want to ask you guys from your experience whats the most effective way of creating diamonds in an oven. I’ve read the pyrex string of posts but was curious if that simple saran wrap method was better than backfilling with nitrogen or other methods you all might have experimented with. Also any advice on gas mixtures? I’m currently running a 40/40/20 mix. I know from trying different blends that it can have a drastic effect on your final product so any thoughts? Thanks for the help.