Firework Star

Firework stars are items used to determine the color, effect and shape of firework rockets.

Crafting
The Firework Star can have three attributes - colors, effect, and shape.

It can have a single color or a combination of up to eight colors when crafted with dyes. There can be any combination of effects but only one shape. Adding one or more dyes to a crafted Firework Star will add a "fade to color" effect to it, overwriting any existing fade colors. Regardless of the dye used, this will not change the color of the firework star icon.

The player can also use multiple ingredients on one recipe.

As a crafting ingredient
Multiple firework stars can be used when crafting a firework rocket, in which case each one will go off simultaneously when the rocket detonates. Adding more than one gunpowder increases the flight duration of the firework rocket.

Trivia

 * Going by descriptions, there are 29,617,272,331,290,536,256 (2.9*10^19) unique firework stars (plus 1 if you count the blank one in Creative mode) and 19,990,120,450,134,546,925,753,238,040,259,571,986,820,916,295,504,403,597,177,411,829,216,667,290,445,679,938,450,910,650,975,366,847,498,729,147,381,808,461,242,200,332,347,927,491 (1.9*10^136) unique firework rockets (plus 3 if you count ones made with blank stars), but going by their visual effects, there are only 2,131,607,154,338 (2.1*10^12) distinct firework stars and 39,675,247,803,502,678,013,047,485,962,163,290,620,857,699,449,061,223,588,692,411,165,364,365,964,747,258,227 (3.9*10^82) distinct firework rockets.
 * Player-made Firework Stars can be dyed any color after they have been crafted. The Firework Star item from the Creative inventory however, cannot be dyed at all.
 * The crafted firework is not available in the creative inventory because there are too many firework combinations.

Feuerwerksstern Vuurwerkster Gwiazdka pirotechniczna Звёздочка 烟火之星