You can synthesize items & weapons at Moogle Shops.

Materials used for synthesis are dropped by your enemies.

There are 50 different materials in whole.

Materials are divided into four ranks- Rank S, A, B, or C with Rank S being the most valuable.

Shards (rank C materials)
Stones (rank B materials)
Gems (Rank A materials)
Crystals (rank S materials)

Crystals are very valuable & hard to find.

Shards & Stones are more common & not as valuable.

Valuable items or weapons require more valuable materials to make.

The better materials you have, the better weapons/items you can make.

Some items or weapons require Recipes to unlock them. You can find these recipes scattered around the Worlds in chests.

Some items you can only make if your moogle is at a high enough level. This is your Moogle LV. Your moogle levels up as you synthesize.

Every item or weapon your synthesize gives you EXP.

The use of a Brightness Material during synthesis (becomes optional Moogle Lv.2) doubles the EXP your moogle will learn for that synthesis.

If you do not have the appropriate ranked Brightness, Energy, or Serenity material- you will not be able to use it during synthesis.

Rank C items/weapons (require shards to make) Lesser weapons/items. You would need a Brightness Shard, Energy Shard, or Serenity Shard.
Rank B items/weapons (require stones to make)
Average weapons/items. You would need a Brightness Stone, Energy Stone, or Serenity Stone.
Rank A items/weapons (require gems to make)
Good weapons/items. You would need a Brightness Gem, Energy Gem, or Serenity Gem.
Rank S items/weapons (require crystals to make)
The best weapons/items. You would need a Brightness Crystal, Energy Crystal, or Serenity Crystal.