In order to add a gem onto your armor you should go to Blython (90,550)
and look for the Gem Converter, give him a gem and he will transfer it
into a diamond acording to the list that you will soon see.
In a case you would like to make a higher level gems there are 3 options:
Give it to the Gem Rookie with 4,000 gold and she will try to attach both gems however,
be awere that this doesn't have a 100% success rate.
Give it to the Gem Master with 4,000 gold and a Legendry Star Dust
(Can be bought from other players or be gained in Lottory Activity),
again, please be aware that this option do not have a 100% successs rate.
The last way has a 100% sucess rate however this is the hardest to do.
Give the gems with a Perfect Star Dust, 2 gem and 4,000 gold; Now the 2 gem will be attached into 1.
Gem and Diamond Properties:
Moonstone Gem: +1 Ice Resist => Silver Diamond +1% Counter Attack Hit/Rate
Emerald Gem: +1 Flash Resist => Green Diamond +1 Combo Hit/Rate
Ruby Gem: +1 Evil Resist => Red Diamond +1 Crit Damage/Rate
Black Gem: +1 Fire Resist => Black Diamond +1 Pirce Damage/rate
Sapphire Gem: +1 Death Resist => Blue Diamond +1% Berserk Hit/Rate
Glimmering Gem: +1 Physical Resist => Yellow Diamond +1% Hit Rate
Purple Gem: +1 Poison Resist => Purple Diamond +1 Speed (grade 1 +2 speed grade 2 +4 spd etc)
Phantasm Gem: +1 Frailty Resist => Gold Diamond +1% Dodge Rate
Soul Gem: +1 Chaos Resist => Cannot be converted to Diamond
Fire Gem: +1 Hypnotise Resist => Cannot be converted to Diamond
Shadow Gem: +1 Stun Resist => Cannot be converted to Diamond