Recently a friend had in possesion some really, really strong meth, unlike anything he had ever tried before. When it was tested with marquis it went orange-brown, only just, and very slowly, like it was very weak. When it was tested with mandelin, it went yellow green in much the same way. I understand that this was not the designed purpose for these testers, but I'm still a little surprised, can anyone shed any light on this or offer similar stories?