Gem colors

Doctor Who: Legacy's core combat mechanic involves the matching of colored gems on a 5x6 field. These gems take six colors—black, blue, green, pink, red, and yellow—five of which are keyed to the attacks of the various characters from which the player can build their team. Below is a breakdown of the six gem colors, what their associated strengths and weaknesses are, and what time fragments are needed to advance a character of the color to the next rank.

 Red

See also: Category:Red allies

Red gems activate the attacks of red characters. Red attacks against green targets deal double damage, while those against blue targets deal half damage. Red enemies are weak to blue attacks.

Blue

See also: Category:Blue allies

Blue gems activate the attacks of blue characters. Blue attacks against red targets deal double damage, while those against green targets deal half damage. Blue enemies are weak to green attacks.

 Yellow

See also: Category:Yellow allies

Yellow gems activate the attacks of yellow characters. Yellow attacks against black targets deal double damage. Yellow enemies are weak to black attacks.

Green

See also: Category:Green allies

Green gems activate the attacks of green characters. Green attacks against blue targets deal double damage, while those against red targets deal half damage. Green enemies are weak to red attacks.

Black

See also: Category:Black allies

Black gems activate the attacks of black characters. Black attacks against yellow targets deal double damage. Black enemies are weak to yellow attacks.

Pink

Pink gems do not activate any attacks, but rather heal the party. Characters of various colors have the ability to shift gems of other colors to pink.

Stone

Stone gems appear only on certain levels, typically those involving the Weeping Angels. These gems can be cleared away in combos as normal, but do nothing aside from adding to the player's combo count. They can be turned into pink gems using the Third Doctor's Reverse the Polarity.

Secondary Color

Rank 5 allies have a secondary color. Each group of matching gems activates both primary attacks from allies with the corresponding primary color and secondary attacks from allies with the corresponding secondary color. Some allies have the identical primary and secondary color and both attacks will be activated simultaneously.

Damage against an enemy is calculated separately for a primary and secondary attack. For instance, Jenny (primary color red, secondary color blue) attacks an Ironside Dalek (green), the red attack will deal 200% damage, while the blue attack deals 50%.

There is currently a bug in the game where secondary attack recive damage boost from boost ability  and wave enhance perk twice, for more details, please look take a look at Boost power and the Combo strength formula.

Summary

Gem Colour
Strong against	Green	Red	Blue	Black	Yellow	Heals allies	No effect
Weak against	Blue	Green	Red	N/A	N/A

Skins

Gems sometimes can change their appearance in some especific levels or events. The first alternate skin was the Christmas one, which was the default skin for a limited time during December 2013, as part of the 2013 Advent Calendar. Since version 2.2 it is possible to select alternative Gem Skins in the "Settings" menu accessible through "Options".

Skin	Red	Blue	Yellow	Green	Black	Pink
Default
Christmas
Van Gogh
Beast
Dalek
Master
Ood
Silent
Roundels
Cybermen

The following is a list of levels featuring alternate gem skins by default. Skins outside from this list are only available by changing the default skin in the Options.

Level	Season	Gem Skin
No Black Gems: Old friends, older enemies part 2	Season 6	Christmas
Vincent and the Doctor	Season 5	Van Gogh
(12th+, Clara+ req.)Sixty Six	Expert Levels	Roundels
Dark water	Season 8	Cybermen