In Infinity Blade II, The Rare Darkfire Gem is a square gem created by fusing together Rare Shock, Poison, and Wind attack gems. Like the rare spectrum gem, this gem grants +500 spectrum attack, but the combined cost of the nine gems needed to forge it is $9,000,000 (the combined sell value being $4,500,000).
3 Darkfire Gems are forged, the result is a Rare Darkfire Gem with +1000 damage, or 10000 damage on a solar-trans blade. The forging of the resulting plus +1000 gem with two subsequent +500 gems results in another +250 per forge (eg. 1000+500+500 >> 1250).
It will not work if the shock, poison and wind gems are not rare. If so, the end gem will not be a Darkfire.
Both the Rare Spectrum Gem and the Rare Darkfire gem have a 10% successful effectiveness against bosses. The solar transport energy blades pin this perfectly, rendering them very effective against the deathless for +1000 spectrum or darkfire gems.
If it is put in a normal weapon, the color of the slahes is yellow and blue. When it stabs, it
has the Infinity Blade's stab animation.
In Infinity Blade III, the Rare Darkfire gem, similar to IB2, is a square gem given to the player after defeating Pisci in Interlude: Dragonslayer. The gem has an elemental force of +1000 spectrum (rainbow). It can be sold for $300,000. It can be upgraded by forging it with two capped elemental attack gems. This will result in a 500 damage increase, and it can be upgraded until 128,000. The second one can be also earned by the Black Fire Map.