The Dungeon Blitz wiki has compiled alot of useful information for crafting here:

http://dungeonblitz.wikia.com/wiki/Crafting

But I wanted to figure out two things:

1. If you want to make alot of gems of a certain type (meaning you want to conserve materials of that type), how much material of that type do you need?

The formula I came up with is

L ≥ ( P + S – D ) / ( 1 + S – D)

L = the total power of the dominant material type

P = the total power needed to create the gem

S = the number of slots I have

D = the number of dominant materials I want to use

For example, if I have 3 slots and I want to make a +4% Trog gem only using 1 trog material, then the power of that material must be at least

( 52 + 3 – 1 ) / ( 1 + 3 – 1 ) = 18

So you need a Trog mat of at least power 18 to make your +4% diamond (using that and two materials of any type of power 17 will get you to exactly 52)

But if you want to use two Trog mats, then their combined power must be at least

( 52 + 3 – 2 ) / ( 1 + 3 – 2 ) = 26.5

You need two Trog mats that have a combined power of at least 27 (and some other mat at least 25).

So that can be pretty useful.

2. If you just want to get your crafting level high, what is the most efficient way to use your mats? In other words, how do you get the most xp per mat?

So I calculated the xp/mat for every possible gem and then ordered them from greatest to least. The higher the x/n, the more efficient that gem is for leveling you up:

https://docs.google.com/spreadsheet/ccc?key=0Ag5Oa4yN4xYmdFNhZFRVTVpqRHpSejRkV291QjE5YlE

The most efficient gem is the Trog +3 (t3) made with 1 mat (n=1), which gives you 8 x/n. The problem with this is that that mat has to be a 24 power Trog, which as some of you may know is very hard to get (the drop rate appears to be broken).

The second most efficient gem is the Sylvan +2 (s2) made with 1 mat. For this you need a Sylvan mat of at least 20 power, but this is pretty easy to farm.

As you can see, this list will show you the way to get the most crafting xp out of all your mats. It also calculates the minimum power level discussed in #1 for each gem. So the minimum Trog power you need to make the t5 gem with 1, 2, or 3 Trog mats is listed under columns Min1D, Min2D, and Min3D.

I hope you can guys can use/understand this stuff. I had fun puzzling it all out!