Attunements are ranked according to how powerful they are. In Valia, they are ranked according to the colour of the shroud they emit. From this attunement level, they are further subdivided into individual attunement rankings starting at E Rank rising through to A-Rank. Spells and enchantments are likewise categorized this way to help determine how powerful they are and how difficult they are to use however it is entirely possible to cast spells and enchantments that are higher than your current level. Such powerful spells and enchantments will require a great deal more mana than spells of the same level as the user and a single spell can easily use up all of an attuned's available safe mana.
The safe usable mana level of an attunement determines how powerful it is. The body naturally uses mana and an attunement also naturally requires a certain amount of mana to run correctly. The amount of extra power naturally generated by the body in the area where an attunement is located determines how powerful an attunement is. Using this mana consistently is how the power of an attunement is grown. It is also how mana levels are improved throughout the entire body. Mana in the body can also be improved without an attunement, as proved by the fact that Corin's strongest area was the hand he uses a duelling cane in. However, exercising the body's mana without an attunement is dangerous and can easily lead to mana scaring. Valia has quantified safe mana amounts and using a complex mathematical formula a diviner can determine how much mana is safe to use in any attunement location for another attuned. As an attuned gains experience they will be able to naturally sense how much mana they have to use.
At the Quartz rank we can see that if an attuned has 24 mana in one area that can be safely used it is considered C Rank. This is the rank that a new attuned will usually have in their attunement location after having just completed their judgment. 25 mana is required to reach Rank B Quartz and to reach Carnelian requires around 60 mana. Since the amount of mana in the region with the attunement determines the rank of the attunement it's possible to have multiple different ranks across different attunements. Attunement ranks get stronger linearly, with a rank E Sunstone attuned being about six times stronger than a rank E Carnelian. Generally speaking, each level of an attunement is roughly six times more powerful than the basic rank of the previous level. Therefore a Rank E Sunstone is still six times more powerful than a Rank E Carnelian. Likewise, a Rank A Carnelian is will have six times more mana to work with than a Rank A Quartz. The levels to reach the different levels and ranks of an attunement are shown in this table.
|Level||Attunement Level||Attunement Ranking||Safe Mana Required|
Sapphire is thought to be purely hypothetical by most of the people on Kaldwyn, but there have been several instances of Sapphire ranked people, items, and spells, including the sheath that Keras Selyrian uses to hold the Sae'Kes, Rage of the God Phoenix, a spell used by Elora Theas that she claims is a Sapphire ranked spell, the brand Katashi places on Corin's hand, and finally Seiryu The God Serpent. Given the fact that Seiryu is Sapphire, and so is Corin's brand, it is highly likely that each of the visages are as well.