無のオーブ [mu no orb] or 'orb of nothing' in Japanese.
Record Keeper

Void Orb (Tiny)
Buy: - (sell: 250 gil)
Use: synthesize and strengthen abilities
Reward: Torna Canal (History)
Drop: (various)
Type: Orb, Rarity: ★, Stack: ?
Description: A minimal-sized orb that holds within non-elemental power.

Void Orb (Small)
Buy: - (sell: 500 gil)
Use: synthesize and strengthen abilities
Reward: Imperial Army Camp (History), Elemental Hollow (Elementary)
Drop: (various)
Type: Orb, Rarity: ★★, Stack: ?
Description: A small-sized orb that holds within non-elemental power.

Void Orb (Moderate)
Buy: - (sell: 1,000 gil)
Use: synthesize and strengthen abilities
Reward: Elemental Hollow (Intermediate), Elemental Hollow (Advanced)
Drop: (various)
Type: Orb, Rarity: ★★★, Stack: ?
Description: A moderate-sized orb that holds within non-elemental power.

Void Orb (Large)
Buy: - (sell: 1,500 gil)
Use: synthesize and strengthen abilities
Reward: -
Drop: ?
Type: Orb, Rarity: ★★★★, Stack: ?
Description: A large-sized orb that holds within non-elemental power.

Void Orb (Huge)
Buy: - (sell: 2,500 gil)
Use: synthesize and strengthen abilities
Reward: -
Drop: ?
Type: Orb, Rarity: ★★★★★, Stack: ?
Description: A huge-sized orb that holds within non-elemental power.
Category: Item