Gems

Gems are prominently featured in several episodes of My Little Pony Friendship is Magic. Unlike actual gemstones, gems in the series are found already cut and polished when extracted from the ground or from rocks.

Appearances
Cut gems are featured throughout the series on jewelery, cutie marks, clothing, and more. Rarity has a particular affinity towards gems: her cutie mark is three lozenge diamonds, and she uses a gem-finding spell in A Dog and Pony Show to get more gems for her gem-studded clothing. Princess Celestia wears a jewel-studded crown and necklace, and the Elements of Harmony are studded with jewels that match the main ponies' cutie marks. In Sisterhooves Social, Sweetie Belle uses all of Rarity's baby blue sapphires to form the shape of a heart and glues them on a drawing.

Spike's gem-eating diet is first introduced in The Ticket Master where he asks the waiter for rubies. He expresses his love of eating gems in several other episodes, and he's shown eating gems in A Dog and Pony Show, Over a Barrel, Owl's Well That Ends Well, Dragon Quest, and Party of One. Both the red dragon in Dragonshy and the green dragon in Owl's Well That Ends Well hoard gold and gems in their lairs.

A Dog and Pony Show
Gems feature prominently in this episode. Rarity runs out of gems for her outfits, and goes searching for them with Spike. She uses her magic to locate gems, and Spike digs them out. When they're finished collecting gems, the Diamond Dogs appear and tell Rarity that they "hunt for gems", then kidnap her and force her to find gems for them in their vast underground tunnel system. Spike recruits the other ponies' help, and they eventually find Rarity and leave with several cart-loads of gems, which Spike happily dines on.

Secret of My Excess


A special kind of gem which Spike and Rarity identify as a Fire Ruby plays a special role in this episode. Spike shows his heart-shaped Fire Ruby to Twilight and tells her he's been aging it to eat it on his birthday. When Rarity sees it, she dotes on it, and Spike decides to let her keep it. Rarity makes a necklace out of it for herself and wears it throughout the episode. After Spike turns gigantic because of his greed, he kidnaps Rarity, who doesn't recognize that it's the same Spike. He tries to steal the gem from Rarity, but she holds on to it and describes how generous is the dragon who gave her the gem. Spike has a flashback to the moment he gave Rarity the gem, and shrinks back to his normal size.

Magic Duel
A red gem is seen on the Alicorn Amulet, a powerful necklace that gave Trixie a lot of magic power. The power of the gem in this episode is used to defeat Twilight in a "Magic Duel." After Twilight finds out Trixie used the Alicorn Amulet to win, she chhallenges her to another duel using a fake amulet given to her from Zecora, and the help from her friends. After Twilight beats Trixie in the duel, Trixie takes Twilight's fake amulet. Rainbow Dash then takes the Alicorn Amulet and Trixie attempts to attack Rainbow Dash with her magic, but shortly Trixie learns that the amulet that Twilight had was actually a doorstop from Zecora's house.