The term “high grade” is used with ore. “High-graders” are mine workers who pocket anything valuable. The mine in San Diego is to the north in Pala.
Any meth in hand can be made high-grade through recrystallization, explained in organic lab books.
Steps in a Crystallization
B. Inducing crystallization
I put cresol red as an indicatior before. I now think it was phenol red I used. The pH range on c.r. is 8.8 to 7.2, on p.r. it is 8.0 to 6.6. Either one would work. Neutral is 7.0. Get a tile and put drops on it; mix in the microscopically minimum amt of sample using the closed end of a melting-pont capillary tube. Do not return sample to batch. Add more conc. HCl a drop at a time, if you go over, add more meth oil. Do not add any other base.
Gassing meth oil dissolved up to a larger volume with diethyl ether makes xls which are automatically neutral.
Do not neutralize meth oil with conc. HCl and shoot it without going through the xl’n step.