How the Violet Cube works and how it differs from Red and Black Cubes

The Violet Cube shows twice as many Potential lines as the item has, and you choose the lines to apply. An item with two Potential lines is shown four, and an item with three is shown six. The cube works only on Rare to Legendary equipment that already has Potentials, and the item text says a maximum rank is not guaranteed.

What the Violet Cube text says

The item text describes the cube in four statements.

It "automatically sets new Potentials". The cube rolls the values for you.
When used, an item with 2 Potential lines displays 4 lines, and an item with 3 lines displays 6.
"You may choose the lines to apply to the item." The roll arrives as a menu of lines to choose from.
It works on Rare to Legendary rank items that already have Potentials. The highest result is Legendary.

The text does not give probabilities, the pool of possible lines, or what happens to the old lines once you choose. It also does not say whether the order of your picks matters or what happens if the game closes during a roll. Those facts are not part of the game's own data, so this guide leaves them out.

The number of lines shown follows the number of lines on the item. The Perfect Potential Stamp adds one line to equipment that has fewer than three, so a two-line item that receives it is shown six lines instead of four.

How the Violet Cube differs from the Red and Black Cube

Each cube below is limited to Rare to Legendary items in its item text, and Legendary is the highest result for each. The differences are in what each cube changes and who makes the final call.

Cube	What it changes	Your choice	Extra text on the item
Red Cube	Randomly reconfigures the Potential	None stated	None
Black Cube	Randomly configures the Potential, not the Bonus Potential	You decide whether to apply the new Potential	Higher chance to raise the Potential rank than Red Cubes
Violet Cube	Automatically sets new Potentials	You choose the lines to apply	Items must already have Potentials
Glowing Cube	Reconfigures the Potential	None stated	Can increase up to 2 ranks according to set probability rates
Bright Cube	Configures the Potential, not the Bonus Potential	You decide whether to apply the new Potential	Higher performance than the Glowing Cube, up to 2 ranks
Memory Cube	Resets the Potential, not the Bonus Potential	You accept or decline before the reset completes	None

The Red Cube is the plain reroll: it replaces the Potential and its text mentions no keep-or-decline step. The Black Cube and the Memory Cube put a keep-or-decline decision on the whole result. The Violet Cube moves the decision to the individual line and shows extra lines to choose from.

Cubes for Bonus Potential

Bonus Potential has its own set. The Bonus Potential Cube reconfigures a piece of equipment's Bonus Potential and "does not affect existing regular Potentials". The Black, Bright and Memory Cubes work in the other direction, and their text says they do not influence Bonus Potentials.

The Bonus Glowing Cube and the Bonus Bright Cube carry the same "up to 2 ranks" line as their regular counterparts, and the Bright version lets you decide whether to apply the result. The Bonus Unicube picks one of the existing Bonus Potentials and sets it anew at the same rank.

Cubes that change one line or equalise lines

The Unicube selects one of the existing Potentials at random and sets it anew, and the rank of the new Potential stays the same. The Cube of Equality resets the existing Potentials so that every line matches the Potential rank of the equipment.

The Miracle cubes

The Miracle line has several versions, and each has its own ceiling in the item text.

The Miracle Cube works on Rare to Unique items, and Unique is its maximum.
The Super Miracle Cube works on Rare to Legendary items and has a greater chance of raising the rank than the Miracle Cube.
The Enlightening Miracle Cube and the Platinum Miracle Cube can upgrade all Potentials to the highest available grade, and the Platinum version is described as having the greater chance to raise rank.
The Premium Miracle Cube cannot be used on Legendary items and needs revealed Potentials.
The Revolutionary Miracle Cube can change the number of Potentials an item has, up to 3, and gives one Super Miracle Cube Fragment.

Availability

Shop stock and sale dates are not part of the game's own data. The Cash Shop in game shows which cubes are on sale now.