[Cygnus Summer Knights Update] Ver 0.73

You can, but it's very inefficient.
10 Low grade > 1 Mid grade
10 Mid grade > 1 High grade
thus, 100 low grade can be turned into one high grade. Seems really dumb but then again if there's an abundance of Low grade diamonds that no one wants, they're no longer valid for quests so there's not much else to do with them.

oh, i didn't know that. my bad.