Sol Emerald

The Sol Emeralds (ソルエメラルド) are a set of seven emeralds of great power that originates from the Sol Dimension. Just like their inter-dimensional counterpart, the Chaos Emeralds, they are usually the sought out by heroes and villains alike due to the great power they possess. They appear in Sonic Rush, as well as in its sequel Sonic Rush Adventure, where they are guarded by Blaze the Cat. They are emerald cut gems, as opposed to the brilliant cut Chaos Emeralds.

Powers and Traits
The Sol Emeralds share many similar traits with the Chaos Emeralds, but they are rectangular in shape (emerald cut) unlike the pointed shape (brilliant cut) of the Chaos Emeralds. Each Sol Emerald possesses unlimited amounts of great power similar to that of Chaos Energy that can be harnessed to empower machinery and creatures alike. Also, if a person harnesses the power of all seven Sol Emeralds, they can be used to achieve a transformation nearly identical to a super transformation (Burning Blaze in Blaze's case). Their powers and theme appear to revolve around fire.

Another thing the Sol Emeralds have in common with the Chaos Emeralds is apparently their ability to convert thoughts into power, although it is unknown to what extent. This allowed Blaze to restore the Emeralds' power after they were drained by Dr. Eggman and Eggman Nega. Also, just like the Chaos Emeralds, if the Sol Emeralds are drained of their power, they will become powerless and look like normal stones.

It is also interesting to note that they possess magnetic properties, another trait they share with the Chaos Emeralds; Both Dr. Eggman and Eggman Nega quote that the Chaos and Sol Emeralds are connected like the north and south pole of a magnet and can therefore attract and repel each other, and can react in each other's presence, and, if in the wrong hands, their power could destroy the world. It is currently unknown if the Sol Emeralds have an equivalent to the Master Emerald that can control them.

The Sol Emeralds share a deep and important connection to Blaze's world and can seemingly draw her world to them, should the emeralds leave their world.

Role in the games
The Sol Emeralds share a similar role with the Chaos Emeralds in the modern games, as serving as necessary plot devices in order for the game's story to progress.

In Sonic Rush, the Sol Emeralds are not collected from Special Stages like the Chaos Emeralds, but are collected after each boss fight where Blaze grabs one from Dr. Eggman. In the story they were under the protection of Blaze the Cat for an unknown amount of time, until Dr. Eggman came to Blaze's world and stole them. Blaze, however, follows Dr. Eggman into Sonic's world and with the help of Cream the Rabbit, she retrieves them one-by-one from Dr. Eggman. In the Final Story of Sonic Rush, Blaze is assaulted by Dr. Eggman and Eggman Nega in their Egg Salamander and they drain the Sol Emeralds of their power. As Sonic comes to her rescue and the Eggmen leave, Blaze is left discouraged due to the Sol Emeralds' powerless state, but thanks to the encouragement from Sonic and his friends, Blaze re-energizes them and uses their power for the first time to become Burning Blaze. She then joins up with Super Sonic and defeats the Egg Salamander, and then returns to her world with the Sol Emeralds.

The Sol Emeralds return in the sequel Sonic Rush Adventure. Like the Chaos Emeralds, the Sol Emeralds have to be collected for the story to progress, but unlike the Chaos Emeralds which are gained from a race with Johnny, the player gets a Sol Emerald after clearing a specific mission. These missions can be obtained from Gardon, but to obtain them all, the player must have unlocked and beaten Hidden Islands 6, 8 and 12. They do not play a role in the story, until near the end of the story where Blaze uses them to become Burning Blaze, while Sonic uses the Chaos Emeralds to become Super Sonic, in order to combat the Egg Wizard. Tails then uses the power from both sets of Emeralds to create a vessel that can bring both him and Sonic back to their own world.

Archie Comics
The Sol Emeralds appeared in Archie's Sonic the Hedgehog and Sonic Universe and serve as the Sol Zone's equivalent to the Chaos Emeralds of Mobius Prime (Sonic the Hedgehog's home dimension). These versions of the Sol Emeralds hold a very important role in maintaining the Sol Zone, and the Zone itself will grow unstable if they are missing from it. Their theme around fire is also more prominent in this media, as a Sol Emerald directly bursted into flames when Shadow tried to use Chaos Control with one of them. Just like in the games, they are guarded by Blaze the Cat.

Etymology
"Sol" translates to "sun" in a variety of languages, and is the origin of the word "solar," which means that the Sol Emeralds translate to "solar emeralds."

Trivia

 * The Sol Emeralds seem to be the reason that Blaze has appeared in Sonic's world on several occasions other than in the Sonic Rush series. In her Japanese profile on Sonic Channel, it is mentioned that she can manipulate the Sol Emeralds to travel through time and space into Sonic's world, and in her 2006 Sonic the Hedgehog profile it is mentioned that she is the guardian of the Sol Emeralds and a princess of her own dimension, creating a direct link between the Sol Emeralds and her otherwise unexplained appearance in Silver's time. In the DS version of Sonic Colors, Blaze also appeared at Sweet Mountain due to the actions of the Sol Emeralds, and in the Adventure Mode of Mario and Sonic at the Olympic Winter Games it is mentioned that Blaze used the Sol Emeralds to travel to Sonic's world to participate in the games.
 * In Sonic the Hedgehog (2006), there are items called Custom Gems that strongly resemble the Sol Emeralds. Each one gives Sonic a new ability.
 * The Sol Emeralds are the same colors as the Chaos Emeralds.