When considering building a character with a high amount of blacksmithing or sagecrafting it would be helpful to know more about the potential benefits of the gems that can be incorporated into equipment.
There are armor, weapon, utility and epic gems. From the names it's somewhat obvious what they are used for (ok utility isn't necessarily crystal clear). Epic gems seem to give the best buffs.
What recipes exist to create epic gems and what stats do they give?
The formatting might still be improved, but here's the info dump for ya. These are from Pristine Quality shards.
Magic+Magic Sorcerer's Gem +1 all unlocked Sorcery skills
Magic+Lightning Gem of Abatement -20% Mana Cost
Magic+Fire Gem of Abatement -20% Mana Cost
Magic+Ice Gem of Abatement -20% Mana Cost
Magic+Physical Warrior's Gem +1 all unlocked Might skills
Magic+Protection Gem of Enlightenment +1 to all first four tier skills in all trees
Magic+Poison Rogue's Gem +1 all unlocked Finesse skills
Lightning+Lightning Gem of Tempest's Vengence 75% chance to shock enemies when Attacked
Lightning+Ice Gem of Magic Resonance +20% Lightning, Fire, and Ice damage
Lightning+Physical Gem of Opulence +20% gold drops
Lightning+Fire Gem of Magic Resonance +20% Lightning, Fire, and Ice damage
Lightning+Protection Gem of the Assiduous +8% more experience
Lightning+Poison Gem of Unrivaled Vitality +50 HP and MP
Ice+Ice Gem of Winter's Vengeance 75% chance to freeze enemies when Attacked
Ice+Physical Gem of Opulence +20% gold drops
Ice+Fire Gem of Magic Resonance +20% Lightning, Fire, and Ice damage
Ice+Protection Gem of the Assiduous +8% more experience
Ice+Poison Gem of Unrivaled Vitality +50 HP and MP
Physical+Physical Gem of the Subjugator +15% Damage and +10% damage resistance
Physical+Fire Gem of Opulence +20% gold drops
Physical+Protection Gem of the Enlightened +10% experience
Physical+Poison Gem of Opulence +20% gold drops
Fire+Fire Gem of Summer's Vengeance 75% chance to burn enemies when Attacked
Fire+Protection Gem of the Assiduous +8% more experience
Fire+Poison Gem of Unrivaled Vitality +50 HP and MP
Protection+Protection Gem of Paralyzing Vengeance 60% chance to stun enemies when Attacked
Protection+Poison Gem of the Assiduous +8% more experience
Poison+Poison Gem of Plague's Vengeance 75% chance to poison enemies when Attacked
