For MerricB
I play each fortnight too, and the way I deal with things like gems is, I make a list with four columns. In the first column I have numbers 1 to 50 or so. In the second I have the values of the gems. In the third, I have a list of what the party thinks the gems are worth via appraise, guessing, etc. In the fourth, I have their descriptions (black opal, tourmaline, etc.). When I give a gem to my players, I tell them its description, and make them note the number of the gem. When they get back to town and sell the gems, I ask them to give me the number, and then reference my sheet. It keeps handy track of things. I can even say things like, "Ah, the gem you appraised at 300gp", while the jeweller realizes it's actually worth more like 500gp, even though they appraised it around a month beforehand.