Well, after a couple of years of playing with the system, I have observed several things that I find interesting, and that I feel could be changed in the use of materials and recipes.

I started to notice than many gems had no use in the system, and others were in such high demand for a variety of crafts, that they were only used in the best item in their group. (For instance Aquamarine Beryl i Boots of Striding +6, Beljuril in Periapt of Wisdom +6, Onyx in Headband of Intellect +6, etc)

So, I decided to go through all the recipes, and make a list of which gems are used and for what.

My findings:

18 gems are only used to make one item.
10 gems are only used to make two items.
9 gems are used to make three items, of these one is used for two versions of the same thing (Effectively making two seperate class of items), and two are use in all three versions of the same thing (ie: Euclase in Rings of Acid Resistance.)
4 gems are used to make four items. Three for multiple version of the same thing. (In effect making three seperate classes of items.)
4 gems are used to make 5 items. Three of them for multiples of the same thing. (In effect 3 seperate classes of items.)
2 gems for 6 items, both of which make multiples of the same thing. (In effect four seperate classes of items.)
1 gem makes seven seperate items, four of which are multiples of the same thing. (In effect only three are seperate classes of items.)
1 gem makes 8 seperate items, two of which are multiples of the same thing. (In effect there are 6 are seperate classes of items.)
1 gem makes eleven seperate items. 4 of which are multiples of the same thing. (In effect there are 6 seperate items.)

Then, there are at least 17 other gems (I may not have a complete list of gems, but I have one of those used in crafting), many of which are high value ones (Padparasha Sapphire, Canary Diamond, King's Tear, Rogue Stone, Topaz, Ruby and Emerald) which have absolutely no use in the game.

My suggestion, is to juggle the recipes a bit, making these non used gems useable in crafting, and reducing the numbers of the high demand gemstones to 3 or 4 items (Groups of Items) tops.

For instance: Rose Beryl's are used for 8 seperate crafted items. [Cutting Star, Regeneration +2 (Amulet), Regeneration +3 (Amulet) (2), Regeneration +2 (Armor), Enhance Guantlets +4, Red Wizard Robes, Spear of Death, Boots of Speed (2)]

Three of these are Regeneration related. I can see them staying as an items for all Regeneration crafted items.

For instance:

But for Red Wizard Robes? Really? Wouldn't Rubies be better for that? They aren't Pink WIzard Robes now, are they?

For the Boots of Speed, wouldn't a Rogue's Stone be more appropriate?

Cutting Star and Spear of Death? King's Tear?

Enhance Guantlets? Topaz, Emerald, Canary Diamond, Padparasha Beryl?

Again, the KEMO 2.0 system is great, but could use some tweaking and fine tuning. The current Gem use for crafts, results in less variety in the long term, as items that would be made for RP and appearance purposes, are not, because the gems needed for them are use in more useful and desired items.