Orb Chests are chests that can be found in the God of War Series, and grant certain orbs, with different abilities, when opened.
Green Orb Chests
These chests are marked by a green glow on top. When Kratos opens it, he'll receive a bunch of Green Orbs for his health meter. In the two first games - God of War and God of War II - the green glow on the top of the chest resembles the head of a Minotaur, which always grants green orbs when killed brutally.
Blue Orb Chests
These chests are marked by a blue glow on top. When Kratos opens it, he'll receive a bunch of Blue Orbs for his magic meter. In the two first games, the blue glow on the top of the chest resembles a snake, probably from a Gorgon's head, because these enemies always grant blue orbs when killed brutally.
Red Orb Chests
These chests are marked by a red glow on top. When Kratos opens it, he'll receive a certain amount of Red Orbs, to upgrade his weapons and magic abilities. Usually, this amount increases through the games, specially near their ends. Also, the orb quantity it grants considerably decreases in the hardest modes of God of War II and God of War III, at the point that some chests don't give any orbs. In the two first games, the red glow on the top of these chests resembles a Harpy.
Gold Orb Chests
This is a rare type of chest found only in God of War II. It is marked by a gold glow on top. When Kratos opens it, he receives Gold Orbs for his Rage of the Titans meter. Only a few are encountered in the game: one in Typhon's Lair, and four gold-blue combination chests in these locations: the Hall of Atropos, the Phoenix Chamber, the path to the Loom Chamber, and the lower level of the Loom Chamber, near Clotho. A few of them appear in God of War III, but only as gold and red mixed chests.
These chests continuously switches between two colors, usually green and blue. In God of War II, some of these chests switch between blue and gold. When Kratos opens it, he'll receive a certain type of orb depending on which color is on the chest when he opens it. In God of War: Ascension, they appear to be an black and gold color.
These chests contain secret special items such as Gorgon Eyes, Phoenix Feathers and Minotaur Horns and usually remain hidden in various locations of the game. In the two first games and God of War: Chains of Olympus, they resemble the other orb chests, but have no colored glow at all. In God of War III and Ghost of Sparta, they are large golden chests, identical to the Überchests from God of War II. In Ascension, they are white glowing chests. If Kratos opens one of these chests with a Gorgon Eye inside having already collected all Gorgon Eyes needed, he will receive a large quantity of red orbs instead of another Eye. The same happens with the Phoenix Feathers and Minotaur Horns.
In God of War III, some chests have two distinct colours. When Kratos opens them, he receives orbs of the two colors of the chests. Most of them are combinations of red orbs and other colors. They usually grant less orbs from each color than a single-colored chest.