This Seeking Tech guide will help you find all the gems in Jeanne d’Arc. There are 17 of these in total, including two that are missable.
Gem of Argent
The Gem of Argent is the first one you will find. You will get it on Stage 2 when Jeanne transforms as part of the story.
Gem of Mistrals
The Gem of Mistrals will automatically be added to your inventory when Gilles joins your party on Stage 6.
Gem of Gules
The Gem of Gules will be added to Jeanne’s armlet after you complete Stage 8.
Gem of Reckoning
You will get the Gem of Reckoning automatically when Richard joins your party on Stage 14.
Gem of Azure
You can get the Gem of Azure as early as after Stage 15, which is when the first season of the Colosseum can be accessible. By beating this free combat stage, you will be able to get the gem. However, you will most likely be under leveled at that point.
If you complete the Colosseum between Stage 21 and Stage 22, then a glitch will prevent you from getting the Gem of Azure. To be on the safe side, you should wait until you progressed through the 22nd stage before completing the Colosseum.
Gem of Light
You will get the Gem of Light when Jeanne get a new armlet as part of the story in Stage 21.
Gem of Levin
By beating Stage 21, you will also get the Gem of Levin for Gilles.
Gem of the Welkin
After Stage 22, you will unlock the Tower of Alsace. By beating this Free Combat Stage, you will unlock Raillemont. You should be able to get the Gem of the Welkin once you complete the Raillemont stage.
Gem of Retribution
By beating Stage 24, you will get the Gem of Retribution.
Gem of Eternity
After Stage 25, you will unlock the Langles Tunnel. Beat this free combat stage to unlock the Gem of Eternity.
Gem of Portent
After beating the Langles Tunnel, the Castle Vilneaux stage will be available. Once you beat this new location, you will get the Gem of Portent.
Gem of Life
The Gem of Life is completely missable since you can only find it as a treasure on Stage 26. This is located behind the altar before you defeat Luxuria.
Gem of Sacrifice
After Stage 26, the Voldor Temple will be accessible. You will most likely be under leveled at this point if you want to be Tiamat. So, you might want to wait until you are at least level 60.
If you complete the Voldor Temple, then you will get the Gem of Sacrifice.
Gem of Guidance
By beating Stage 31, you will get the Gem of Guidance.
Gem of Blood
The Gem of Blood will automatically be added to your inventory when Roger gets an armlet.
Gem of Darkness
After you beat Stage 36 and reload your clear save file, you will be able to access the Cemetery in the postgame. Complete this stage to get the Gem of Darkness.
Gem of Miracles
The Gem of Miracles is a reward for beating the second season of the Colosseum in the post game. You can only access this season if you beat the first season of the same stage in addition to beating Stage 36.
Before you try the second season, make sure you are at least level 80.