I know astral diamonds became standard official currency in 4th edition, but I'm nigh-certain they existed in 3rd edition, if not 2nd. I can't FIND information about it, hence asking the question, but I know people at my FLGS referenced astral diamonds as bargaining chips for diabolic deals in 3rd edition, and my memory tells me either planescape or spelljammer was the source. Editing question to include.

---unless you assume material properties non-existant in the real world. Which is what I was going to do. Basically magic, but MEASURABLE magic.

Fair point. Part of the purpose of doing these physics calculation is just recreational, but the other part is to be able to tell my players exactly how awesome their high level characters are, maybe using some modern-day weaponry comparisons to get the point across. "You slice right through a tendon, something that a fighter jet mounted minigun wouldn't be able to do" is the sort of narration that can get a player pumped and excited.