Emma Frost's (Marvel) secondary mutation is a pure diamond form.
have a body made up of crystal or crystalline substance
transform into or have a physical body made up of crystal or crystalline substance. Variation of Earth Mimicry and technique of Crystal Manipulation.
User is made up of or can transform their body completely into crystal or crystalline substance. Users transformed form can be either anatomically identical to their normal form, aside of being made of crystal, in which case it contains all to organs and is somewhat vulnerable to attacks. Alternately user can transform into homogenous matter, without any part of their form being more important than the other.
Users of Sound Manipulation would be able to shatter the crystal.
While hard, many crystals have flaws that may be used to shatter them completely. This may be true to the users of this power also.
Emma (X-Men Origins Wolverine)
Diamondhead (Ben 10) is a Petrosapien, an alien-race of creatures of pure diamond.
Chromastone (Ben 10) is a Crystalsapien, a race of crystal-like aliens that can absorb and expel energy.
Amethyst (Steven Universe)
Sapphire (Steven Universe)
Rose Quartz (Steven Universe)
Lapis Lazuli (Steven Universe)
Peridot (Steven Universe)
Yellow Diamond (Steven Universe)
Emma Frost (Marvel) in her diamond form.
Stepford Cuckoos (Marvel)
Ruby Summers (Marvel) daughter of Emma Frost and Scott Summers in the alternate future/universe.
Crystal Beasts (Yu-Gi-Oh!)
Jozu (One Piece) changing his skin into diamond.
Hosenki (InuYasha) is a demon composed of diamond and can shoot diamond spears.
The Crystal Onix (Pokemon)
Gnorcs (Spyro the Dragon) are a race of monsters created when Gnasty Gnorc used his magic to make an army from the Dragon's stash of gems, turning back into gems when they are killed.
Crystal Flowers (Spyro: Year of the Dragon) are monsters created when the Magicians of the Crystal Islands messed with the Sorceress's magic.
Crystal Bears (Spyro: Year of the Dragon) are monsters created when the Magicians of the Crystal Islands messed with the Sorceress's magic.
Mephiles the Dark (Sonic the Hedgehog) can manipulate the crystal structure that composes his body.
Zoah (Sonic the Hedgehog)
Demon Lord Ghirahim (The Legend of Zelda: Skyward Sword) has a crystal in his chest that is his only weak spot.
Urcaguary (Valkyrie Crusade)
Urcaguary (Valkyrie Crusade); at a higher level
Urcaguary Ex (Valkyrie Crusade)
Urcaguary Ex (Valkyrie Crusade); at a higher level
When Team Miasma steals the Zafiro de las Lágrimas, the cursed Sapphire created a monstrous entity known as The Presence (Grindhouse and Watercolors), a shadow that forever haunts the group to this day.