Emerald was a shade of green called after a certain gemstone.
The Third Doctor wore an Inverness cape of scarlet and emerald tartan during his first visit to Peladon. (TV: The Curse of Peladon) He also wore a blazer of emerald velvet with a notched collar when he and Sarah Jane Smith helped to save Peladon from Ice Lord Commander Azaxyr and Eckersley. (TV: The Monster of Peladon)
The Fourth Doctor wore an emerald tie when he met the K1 Robot, (TV: Robot) when he faced Wirrn, (TV: The Ark in Space) when he fought Field Major Styre of the Sontaran G3 Military Assessment Survey and tricked his marshal into cancelling an invasion of Earth, (TV: The Sontaran Experiment) when he first met Davros who forged the first Daleks during the Genesis Incident, (TV: Genesis of the Daleks) and when he faced Nomad Cybermen during their gambit to destroy Voga after the Great Cyber War. (TV: Revenge of the Cybermen)
After his clothes were ruined by a Xaranti, (PROSE: Deep Blue) the Fifth Doctor wore a white shirt with an emerald lining. (TV: The Awakening-The Caves of Androzani) His successor, the Sixth Doctor, wore it during his first hours; (TV: The Caves of Androzani) before changing for a white one with a cherry lining. (TV: The Twin Dilemma)
The Eighth Doctor wore a cravat of emerald dupioni when he, Charley Pollard, and C'rizz confront the Kro'ka. (AUDIO: Caerdroia)
The War Doctor wore double-breasted waistcoat of emerald moleskin with a shawl collar and a double fob chain of bronze when he and Skole faced Valmoria during the Last Great Time War. (AUDIO: In Name Only)
Ace wore an emerald t-shirt under a black cardigan when she and the Seventh Doctor worked with UNIT to stop Morgana and the Destroyer. (TV: Battlefield)
Amy Pond wore an emerald t-shirt under her navy blazer. (TV: The Lodger)
Jo Jones wore an emerald and ivory ikat scarf with rust orange symbols when she reunited with Clyde Langer on the Memory TARDIS. (TV: The Three Doctors)
Bliss wore an emerald jumper. (AUDIO: The Famished Lands)
Rose Noble wore an emerald green jumper when she met the Fourteenth Doctor, Beep the Meep, and some Wrarth Warriors. (TV: The Star Beast)
Bill Potts wore an emerald velvet pelisse during a visit to the 1814 frost fair. (TV: Thin Ice)
The Twelfth Doctor wore an emerald hoodie during his adventure with Bill Potts. (TV: The Pilot)
Peri Brown wore an emerald mini-skirt when she and the Sixth Doctor went to Titan III and Jaconda during 2310 (TV: The Twin Dilemma)
The sixth incarnation of the Corsair wore emerald breeches. (COMIC: Old Friends)
The Reborn Master wore an emerald cravat when posing as 'the other Doctor'. (AUDIO: Dominion)
The Warrior, a parallel version of the Fifth Doctor who looked as the Sixth, spent his first hours in his predecessor's emerald tie before switching for scarves; each similar to the ones worn by the War Doctor of N-Space. (AUDIO: Dust Devil)