Crystal Ponies

Crystal Ponies are a kind of ponies which inhabit the Crystal Empire and first appear in the season three premiere. Crystal Ponies are distinct from other ponies by their shiny, gradient manes and tails, and most of the time, polygonal shaped irises.

Depiction in the series
Before the Crystal Ponies appear on screen in The Crystal Empire - Part 1, Princess Celestia describes the Crystal Ponies' magic power to Twilight Sparkle: she says that if their kingdom is "filled with hope and love, then those things would spread all across Equestria." The Crystal Ponies are introduced soon after the Crystal Empire returns from its 1000-year absence due to King Sombra's curse. Twilight and her friends journey to the kingdom at Celestia's behest, and when they get there, Twilight sends her friends to interview the Crystal Ponies to learn more about their culture.

She then meets one of the Crystal Ponies herself, and confirms to the pony that the Crystal Ponies have been "gone a thousand years", while the Crystal Pony goes on to say she remembers nothing of the time before King Sombra's rule, and that she does not "want to remember" anything about the duration of his rule. None of the Crystal Ponies the main characters meet can remember much about their history. A librarian they meet can't even recall if she works at the library. The Crystal Ponies look glum and dull, and talk in low, monotone voices. Twilight Sparkle speculates that King Sombra's spell must have caused the Crystal Ponies to lose the crystalline colors of their coats.

The ponies don't discover much and decide to head to the library, where they find a history book of the Crystal Empire and learn from it. In the Ballad of the Crystal Ponies, the seven main characters set up a "Crystal Fair" to preserve the Crystal Ponies' culture and remind the Crystal Ponies of their heritage. The friends learn that the Crystal Ponies used to joust, make flags, make sweets with crystal berries, have petting zoos with "tiny ewes", play crystal flugelhorns, and sing the Crystal Kingdom anthem.

As the ponies try to lift the Crystal Ponies' spirits, the Crystal Ponies regain their crystalline colors one by one. One pony exclaims to her friend that she is starting to remember things "from before the king". After Princess Cadance defeats King Sombra using the Crystal Heart, which is powered by the Crystal Ponies' combined magic, the Crystal Ponies completely regain their crystalline, translucent colors. The main ponies, Spike, Shining Armor, and Cadance gain a crystalline appearance too, but it wears off by the end of the episode.

Some Crystal Ponies appear in Just for Sidekicks, and more appear in Games Ponies Play, where both episodes' plots occur in a unison timeline of each other. The Crystal Ponies in these episodes are crystalline and sparkly.

In Magical Mystery Cure, they appear in Ponyville when Twilight is singing the Morning in Ponyville song and later in Canterlot during Life in Equestria.

Crystal Pony royal guards appear in My Little Pony Equestria Girls, welcoming the newly crowned Princess Twilight and her friends to Twilight's first princess summit.

In Rainbow Falls, several Crystal Ponies appear in the crowd of ponies at the Equestria Games qualification tryouts.

In Three's A Crowd, a Crystal Pegasus royal guard appears alongside Princess Cadance during her arrival in Ponyville.

At least one Crystal Pony appears at the Rainbow Falls Traders Exchange in Trade Ya.

Other depictions
The blurb advertising the Shout! Factory DVD Adventures in the Crystal Empire proclaims that the Crystal Ponies "suddenly appeared in the arctic north of Equestria" alongside the Crystal Empire. The DVD cover depicts the six main ponies with the appearance of Crystal Ponies. While Applejack, Fluttershy, Rainbow Dash, and Twilight Sparkle all have polygonal eye reflections, and in Applejack's case polygonal freckles, Pinkie Pie and Rarity have their usual rounded eye reflections. Whilst these ponies, as well as Spike, are not Crystal Ponies, towards the end of The Crystal Empire arc they all did sustain the attributes of Crystal Ponies when the magic of the Crystal Heart had exploded into enlightening the Empire back into its full spirit whilst the characters were in its vicinity. The effect is only temporary for these characters, and wears off by the end of the episode.

Playful Ponies toys in the Crystal Empire and Crystal Princess Celebration lines depict Applejack, Fluttershy, Pinkie Pie, Ploomette, Princess Cadance, Princess Celestia, Princess Luna, Rainbow Dash, Rarity, Sunset Shimmer, Twilight Sparkle, and Twirly Treats with the appearance of Crystal Ponies. A blurb on the Crystal Empire packaging of one such Fluttershy toy states that "FLUTTERSHY has a tea party to make friends with the CRYSTAL EMPIRE ponies—they seem just as shy as her!"

Hasbro-licensed translucent Special Edition Crystal Pony keychains of Pinkie Pie, Rainbow Dash, Applejack, and Rarity made by Basic Fun were presented at the February 2011 Toy Fair; later in 2011, Pinkie Pie and Rainbow Dash were first released, and in 2013, Pinkie Pie and Rainbow Dash were released again and Applejack and Rarity were first released.

The picture book "Welcome to the Crystal Empire" consistently spells "Crystal ponies", features a jousting Pegasus pony regarded as a Crystal Pony, reads that the Crystal Ponies' "coats were so dull [in the episode The Crystal Empire - Part 1] because King Sombra had erased their memories and stripped them of their love and light. [...] It's that special magic that makes their coats sparkle so brightly" and mentions "their shiny crystal fabric".