|Spoiler Alert: This article/section contains details about future plot lines described in the light novels, not covered in the anime. Do not proceed unless you want to be spoiled.|
In order for a Sephira Crystal to turn a human into a Spirit, they simply need to touch it. The gem is then absorbed into the one who touched it and will turn that person into a Spirit. When Origami was being turned into a Spirit, she described the feeling as "as if a second heart was being created inside her".
Human beings have varying levels of compatibility for becoming a host for the Sephira Crystals, with Phantom stating that Origami was an exceptional user due to wielding her angel so skillfully.
As seen from Kotori's example, Sephira Crystals can be toxic to the host's body, and can even induce madness. As a result, Mio stated that they need to be further refined by killing the initial host and then transplanting the gem into another host. Doing so, would ensure that the Sephira Crystals will come closer to completion and resolve the negative drawbacks. According to Mio, while the attributes of each Sephira Crystal is pre-determined, the powers that manifest can vary depending on the personality of each host.
So far, there have shown to be three ways for a Sephira Crystal can be removed from a Spirits' body. The first method is to kill the Spirit. Second, seal all the Spirits' mana in Shido's body and then use a Realizer to remove it from his body in the form of a new Sephira Crystal. Finally, Artemisia has also shown the ability to remove a Qlipha Crystal through unknown means by using her territory. Ellen also says that she possesses a similar ability. Mio has also displayed the ability to removal Sephira Crystals from their hosts by using her Angels and Astral Dress as a weapon. However, Mio's method ultimately leads to the death of the former host. Also according to Mio, it is possible to destroy a Sephira Crystal by gathering Reiryoku in her hand to crush the crystal, although it is unknown whether other Spirits can do so as well.
According to Inverse Tohka, the Sephira Crystals first emerged as Qlipha Crystals when the First Spirit decided to divided her power. The Inverse Spirit later speculates that she reversed their properties into Sephira Crystals in order to make them more compatible for human hosts.
When creating the Sephira Crystals, Mio split off and condensed a portion of the reiryoku. Along with her power, the Sephira Crystal were breathed with a portion of her emotions as well, with the color being determined by which particular feeling was strongest during its creation. If the emotion was wrath, it would be a fierce red. For blue, it was be a sorrowful blue. If it was regret, it would be a bottomless black. The more negative the emotion, the stronger the Spirit would become. However, that also increased the toxicity of the Sephira Crystal as well. In order to purify the Sephira Crystal, she would use humans as sacrifices. Each time the Sephira crystal went through a new host, it would become slowly purified as if undergoing a filter treatment. Those that were used as 'filters' lost control of themselves when given a freshly made Sephira, going berserk and attacking everything in sight. This caused Mio to need to repeat this process numerous times, transplanting the Sephira into numerous hosts until it was fully purified.
One day, Mio wondered if it was possible to create a fully purified Sephira from the beginning. To do this, Mio used the strongest emotion that was source of all of her motivation: love. She concentrated her mind and separated the so-called “poison” that could harm humans into a place inside Sephira. However, that produced the unexpected effect of a Sephira gaining its own will. This Sephira would later develop into the second pure Spirit after Mio, growing to eventually become Tohka Yatogami.
List of Crystals
|Camael|| Sawa Yamauchi |
|Raphael||Kaguya Yamai & Yuzuru Yamai|
|Rasiel|| Nia Honjou|
- The Sephira Crystals are named after the Sephirot Tree, the tree that the Spirits are based on.
- The base text "霊結晶" reads "Reikesshō", which literally means "Spirit Crystal".