I want to propose to make “Skill Gems Collections”. For example:
Archer Collection:
Multi Shot Gem
Oblique Shot gem
Swift Step Gem
Twin Arrow Gem
Concentration Gem
Leap Gem
Effect: All Skill lvl of Archer +1
Moreover, if the idea about “skill gem collections” becomes true, i want to propose to remove the possibility to put skill gems on equipment, and rework the “normal” ones (Blue, Yellow, Green, Red and White gems) to make them more versatile (make them able to give more kind of bonuses (all the possible stats from random ichors except base stats (DEX, CON, SPR, INT, STR) plus other ones (like HP, SP, AoE attack/defense ratio, etc)).
The idea is to make “normal” gems like unpolished stones (like colorless gems) that players have to polish. This system is like “identify” system from unidentify equipment, which means that new gems could give different stats (but only one per gem (not up to 2 (trinket) or 6 (two-handed weapons) like on equipment), and have different rarity aswell.
Rarity should be defined by the lvl of the gem:
1 - 2 Normal
3 - 4 Magic
5 - 6 Rare
7 - 8 Unique
9 - 10 Legend
The stat values from the gems will be different depending on the lvl of the equipment where you put it and the lvl of the gem.
Moreover, i want to propose to remove 2 colors from “normal” gems to divide them into 3 categories: Attack (able to be put on weapons), Defense (able to be put on armor) , Utility (able to be put on accessories).
Number of gems per equipment:
Bracelets x1 (x2)
Necklace x2 (x1)
Armor x1 (x4)
1-Handed weapon x2 (x1)
Sub-weapon x2 (x1)
2 Handed-weapon x3 (x1)
Trinket x1 (x1)
4 attack, 4 defense and 4 utility in total.
The skill “Gem Roasting” from Alchemist could be changed to “Gem Polishing” and used to identify/polish unpolished stones and discover what does it have inside it (66% chances to get a random abrasive (from lvl 2 to lvl 5), 33% chances to get a random “normal” gem and 1% chance to get a random skill gem). discovering the color, stat and rarity from gems aswell.
Futhermore, if the idea becomes true, i think that the “gem leveling system” (level by experience) should be removed but the level on gems should be maintained to define the rarity. This means that “gem abrasives” should not be removed but it should work in other way (like combine/fuse/roast different abrasives to make a new one with higher lvl or something like that. Just another way).
Moreover, if this idea becomes true, i think that the rarity of the “normal” gems should be keeped, reduced or destroyed randomly (33,3% keep rarity. 33,3% reduce rarity to a random lower rarity. 33,3% destroy) when a player decides to extract it from an equipment.
This gems should be able to be destroyed to get a gem abrasive of the same lvl of the gem destroyed (skill gems could be destroyed or used to other stuff aswell).
Geraldasia should give Unpolished Stones instead of the color ones.
The Alchemist Master should be able to do the Gem Polishing too (like identify from blacksmith), which means that the chances from the Gem Polishing skill from alchemist should differ by the lvl of the skill (which means that the Alchemist Master should have lower chances to give both kind of gems and high chances to give abrasives (like level 1 Gem Polishing from Alchemist or something like that. The Max. level of the skill could be only 1, but in that case, Polishing on alchemist shops should be better than polishing on the Alchemist Master (like what happens with repair and identify on blacksmith)).
Skill gems could be used in other kind of stuff/equipment/system aswell, but the proposal of this post is about make the “normal” gems more usefull than the current ones, and make usefull all skill gems because the idea about use all to complete collections (this collections could be obtained from a special quest from each class master for example).
All what i said is just an idea (it could be in other way or just take a part of the ideas, not all).
I hope you like the idea!! 
Cheers