Depending on the skill and willpower of the wearer, it can do almost anything. The first Green Lantern Ring on Earth in modern times was crafted and worn by Alan Scott and powered by the mystical Starheart. His proved to be the exception, the by-product of the efforts
A Green Lantern Ring, also known as a Power Ring, is a piece of jewelry that grants the wearer incredible and incomprehensible powers and abilities by harnessing willpower. They are considered by some to be the most powerful weapons in the known universe.
Depending on the skill and willpower of the wearer, it can do almost anything. The first Green Lantern Ring on Earth in modern times was crafted and worn by Alan Scott and powered by the mystical Starheart. His proved to be the exception, the by-product of the efforts of the Guardians of the Universe to contain the magic of the universe. The Guardians also created the more widespread version, powered by individual Green Lantern Power Batteries through a connection to the Central Power Battery on Oa. With the exception of the ring worn by Alan Scott, the current rings are based on the one given to Kyle Rayner when he was the only Green Lantern in existence.
Main article: Pre-Crisis
Originally, on Earth-One dimension, the first Green Lanterns were equipped with pistols, not rings, which were recharged in lantern-shaped batteries. Beginning with Rori Dag from Rojira receiving the first power ring,  those other proto-Green Lanterns presumably gained rings and were invited to participate in the new Green Lantern Corps soon after. In the Post-Crisis, however, the Green Lantern Corps always wore power rings, though their predecessors, the Manhunters, used pistols.
Oan Power Ring
In the days of the original Green Lantern Corps, the Guardian known as Meadlux created a power ring specifically for the Guardians. An Oan power ring possessed the same capabilities as a standard ring, but was fueled by the internal power of its wielder and thus did not need to be recharged. Unlike the traditional Green Lantern Ring, an Oan ring did not contain the impurity that restricted its capabilities against materials colored yellow. The revelation that such a weapon existed caused a great schism within the ranks of the Green Lantern Corps. Officers who had lost close comrades due to adversaries empowered by yellow weaponry lost faith in the Guardians. Some of whom, such as Galius Zed, Eddore and Kaylark even went so far as to turn their backs on the Guardians, coveting the rings for themselves. Another group of individuals who took an interest in the Oan rings were the space pirates known as the Free Lancers.
Honor Guard Power Ring
There is no known difference in power and ability between the ring of the Honor Guard and the ring of a normal Green Lantern. Only the Honor Guard ring design is different. This was the ring first worn by Kyle Rayner when the Corps was destroyed, and was the first ring to use the new recharging protocol of only needing to be recharged when the ring is depleted. Instead of once every full planetary rotation (24 hours).
When in the vicinity of a Blue Lantern, or someone wielding a Blue Lantern Ring, any Green Lantern Ring can be charged to 100% and beyond. An overcharged ring allows its user to travel faster, create larger and stronger constructs, and exert incredible amounts of energy. There is no known limit to which a ring can be overcharged to, but the highest seen is 325%.
All power rings need periodic recharging. The process is not instantaneous so many Green Lanterns recite an oath while the ring charges. The oath is not required to charge the ring, but is recited to reaffirm the person's commitment to the Green Lantern Corps, and to measure the time it takes the ring to charge. While many Green Lanterns create their own oath, the majority use the Corps' official oath as a sign of respect. In the interests of political correctness on the part of DC (or, in context, Hal Jordan), the word "blackest" was replaced by "darkest"; this practice has been abandoned with the reinstating of the Green Lantern Corps due in part to the significance of the Blackest Night comic event. Rot Lop Fan, a Green Lantern from a starless sector, replaces sound with light in his oath.
"In brightest day, in blackest night,
No evil shall escape my sight.
Let those who worship evil's might,
Beware my power... Green Lantern's light!"
Bright Green Energy Conduit: The rings use pure energy supplied by a Power Battery, which in most cases takes the form of bright green light. This energy is the green light of willpower of the Emotional Electromagnetic Spectrum. Rot Lop Fan, from a race without eyes, perceives it as the sound "F-Sharp" and his 'ring' is actually a bell. A Green Lantern's ring, considered by some to be one of the most powerful weapons in the known universe, has the ability to affect and use fundamental forces of the known universe, including electromagnetic energies such as gravity, radiation, heat, light, and powerful blasts of concussive force. It is also theorized that the ring also has a basis in other dimensional energies commonly called magic by users of such energies. The ring can also create fields of force formed from an unknown energy that is bound by the users' will. The limitations of such use are the skill, knowledge and imagination of the user. Some of the abilities that a Green Lantern Ring has shown are:
- Energy Projection: The ring can be used to fire blasts of Oan energy or create weapons such as projectiles of them. The ring can project beams of force powered by the will of the user. The ring can be used to produce kryptonite and kryptonite radiation. Kyle generally used fanciful constructs in the shape of advanced technology. Their appearance does not indicate the power of the weapon. The weapon's power is more an indication of the will of the user. Certain users (i.e. Hal Jordan) have been powerful enough to stagger even Superman. If the user wishes, they can alter the form of the blasts such as Kilowog's "booms." Code 1012 is a protocol to incinerate all extraterrestrial weapons and technology in the area.
- Force Field: The ring can create various force fields of various sizes and shapes to protect the wearer and others around him. With the cosmic scope of a Green Lantern's duties, it is only natural that the power ring is designed for operation in space. The ring creates a force field around the wearer, protecting him/her/it from the hazards of the void including filtration of stellar radiation and microscopic particulate matter which would ordinarily be fatal should the space debris strike the ring wielder at high speeds. An atmosphere appropriate to the ring wielder's biology is created inside the force-field while body temperature is maintained and waste products are removed. Gravitational stresses which could cause injury are stabilized for the ring wielder. Theoretically, a ring wielder could use the ring as his/her/its sole source of life support. The force field seems to be created instantaneously whether this is due to programming or an instinctive reaction from intensive training has not been established. It could be considered as a subroutine of the ring's automatic defensive system, but as of yet this theory has not been proven. The only exception to that was attacks based on the color yellow. The newer version of the ring is not limited by the color yellow.
- Energy Construct Creation: The ring can form constructs of Oan energy. The primary function of the Power Ring is to provide a weapon capable of transforming the wearer's thoughts into physical constructs through the wearer's strength of willpower. A Green Lantern can create any particular items or construct that they can imagine as long as they have the willpower necessary to will it into existence. The constructs are made out of bright green energy, which is a tangible form of pure willpower, and they exist only as long as a Green Lantern is fueling it with their willpower. Items created by the rings are not indestructible and are only as powerful as the willpower of the Green Lantern creating them. The types of constructs usually reflects the ring wearer's personality. For example, Kyle Rayner was an artist, so his constructs reflect his strong imagination. John Stewart is an architect so his constructs often appear mechanical as if he designed them in his mind before making them a reality.
- Superhuman Strength: While not super strength of the conventional sense, a Lantern while using constructs created by the ring becomes capable of lifting/moving tremendous weights far heavier than 100 tons with little effort.
- Phasing: The Power Ring allows the wearer to pass through certain solid objects such as walls. Which objects that are not penetrable are not known, but it may depend upon the strength of the wearer's willpower and the density of the object's molecular structure.
- Environmental Playback: Upon request, the power ring can recreate a holographic environment based on data in its memory banks. The ring wielder can observe events in a ghostlike state, but the ring wielder cannot alter the outcome of the playback. All objects in the playback will appear in the full spectrum of colors, regardless of the wielder's level of expertise creating simulacra. The power ring will automatically end the playback if outside interference warrants the ring wielder's undivided attention.
- Will Empowerment: Emerald power rings can be further magnified by the amount of will a user possesses. A wielder can not only ascertain incredible strength if their will is strong enough, but the strongest of wills also acts as a surrogate means of recharging; and in some cases, supercharging their power ring in case they are low on energy at the time. The only drawback being if their will is too strong, the ring may explode. Taking the wearer with it.
- Invisibility and Light Refraction: A ring wielder can render him/her/itself invisible by willing the ring to bend light waves around his/her/its form, as well as that of the power ring. Presumably, a similar action allows an experienced ring wielder to create objects of colors other than green. As Hal Jordan's experience grew, he was able to create power ring illusions of people and objects. It can be assumed the ring wielder would not risk the extra time and effort to create other colors in a combat situation. An invisibility shield was used by Hal Jordan to hide his power ring, which would only become visible when he changed to Green Lantern.
- Emerald Sight: An as of yet unexplained power in which the Green Lantern can obtain, is the ability to divine the future in glimpses of bright radiance. So far Mr. Baz is the only lantern with the power to date.
- Energy Twin: The power ring allows the wearer to create an "energy twin" of his/her/itself that can travel at far greater speeds than that of the ring wielder's physical form. While the energy twin is active the ring wielder remains motionless, his/her/its life force is needed to guide the energy twin. The energy twin can not alter its surroundings and may only be perceived by the Guardians or another ring wielder as a green, ghostlike image. Any knowledge gained by the energy twin is transferred back to the ring wielder's physical form upon recontact with the body. The Guardians frequently used energy twins as a means of contacting a Green Lantern. As a rule, a ring wielder can not create actual, independent duplicates of him/her/itself, as the power ring cannot create life.
- Energy Absorption: The ring can absorb and store other energies. Doing so does NOT replenish the normal store of energy the ring has. A ring that needs recharging but contained a store of electricity could only discharge that electricity, for example.
- Flight: By the manipulation of anti-gravitons and directed molecular movement, the ring allows the user to fly at incredible speeds. In atmosphere, a Green Lantern has been known to fly as fast as Mach 10 in atmosphere by creating an aerodynamic envelope around his body. Towing others, usually within a bubble, his speed is limited to the twice the speed of sound or 1440 mph. In space, Green Lantern's speed can be significantly greater and has been known to approach 99% of light speed in normal space. Flight has been shown to be velocities far exceeding light speed. In atmospheres, air friction is not a hindrance since heat is either absorbed or reflected by the ring's field.
- Wormholes and Spatial Warps: The power ring grants its wearer access to wormholes in space, enabling the ring wielder to rapidly cut time and distance needed for transport. The Guardians established at least one known wormhole to Oa, which once required the use of a power ring to enter. Black holes can be navigated by experienced ring wielders. During a battle with Sinestro and his ally, MadGod, members of the Green Lantern Corps of Earth and the Green Lantern Corps of the Klyminade traveled through a black hole to be deposited outside a white hole in Sector 872. The power ring cannot generate a Boom Tube as it needs a Mother Box powered by a sample of the highly unstable Element X. There is no known way to duplicate either item even with the power ring. Should a Green Lantern make his/her/its way to the other-dimensional worlds of Apokolips or New Genesis through a Boom Tube, the ring will function as it does in the rest of the universe. John Stewart encountered no ring related difficulties during his stay on New Genesis, despite the loss of the Central Power Battery. The ring wielder would still need a Boom Tube to return to his/her/its dimension.
- Time Travel: Time travel is possible with the power ring, though the further forward in time a ring wielder travels, the more willpower it takes. As Green Lantern, Hal Jordan once explored as far as the 70th century. Jordan had also traveled to the 58th century as Pol Manning, a role later adopted by Salakk of Slyggia. The ring also granted the wearer the ability to communicate telepathically with other people from different points in time.
- Limited Cellular Regeneration: The ring has an ability to heal physical injuries; this seems to be a feature held over from the previous incarnations of the ring. Green Lantern can use the ring to repair injuries in himself or others. Speculation has been rendered that if Kyle actually had medical knowledge he would be able to cure a wider variety of dysfunctions beyond normal physical injuries. Simon Baz has used the ring to maculous degrees in healing and restorative capacities; having brought his brother-in-law out of a coma using his ring.
- Electromagnetic Scanning: The ring has a wide range of detection abilities based on the imagination of the user. If one can conceive of it, he can probably detect it. Magical effects like clairvoyance seem to be beyond the scope of the ring. Most normal electromagnetic phenomena are within the range of the ring, including radio, radar, television, infrared, ultraviolet, microwave, and high frequency band communications.
- Galactic Encyclopedia: The earlier rings worn by the Corps functioned as references for their users. Having the vast knowledge of the Book of Oa to draw upon, each ring functioned as a ready reference on most peoples, stellar events and conditions that may have been seen by other rings or other Green Lanterns. The rings also served as a repository of adventures had by the Green Lantern and these mission reports were stored in the Prime Battery on Oa for review and training.
- Universal Translator: Keeping in mind the myriad of worlds, life forms, and cultures throughout the cosmos, it is understandable why the Guardians added a translation system to the power ring. The power ring can translate virtually any language in the universe, facilitating diplomatic encounters rather than violent confrontations. Complications arise when a frame of reference for translation is not available, as evidenced during Katma Tui's induction of Rot Lop Fan into the Green Lantern Corps. Katma Tui had the difficult assignment of explaining the concepts of "light" and "color" to the sightless Rot Lop Fan. She overcame this barrier by using sound rather than light as the basis of the ring's power. Some Green Lanterns, such as the planet form known as Mogo, have used the ring to create an intermediary "being" to expedite communication. However, this ability seems less effective since the restoration; it is possible that not all the data was recovered.
- Material Alteration: The Green Lantern's uniform is not made out of fabric. It is created by the Power Ring whenever the wearer wills to wear it. It automatically appears over the wearer's normal clothing, and vanishes when the wearer wills to return to their civilian attire. Most Green Lanterns wear similar uniforms that are programmed into the ring by default such as Hal Jordan's uniform. However, each Green Lantern is able to adjust their uniform to fit their own needs, personalities and whims. For example, Kyle Rayner was unsatisfied with the traditional Green Lantern uniform and created several of his own designs. John Stewart's uniform is similar to Hal Jordan's, but lacks a mask to hide his identity. Jack Chance is the most extreme example, refusing to wear a uniform save for a Lantern badge on his trench coat. The green parts of the wearer's uniform are usually very warm or hot to those who touch it, while the black parts are very cold. The uniform also produces a "siren" taking on the form of the Green Lantern Corps' symbol, circling the Green Lantern when active. The symbol, or badge, will not appear on the uniform until after a newly inducted Lantern has completed training on Oa, leading to the term "White-circle" to describe a rookie Lantern.
- Ring Duplication: Most Power Rings are capable of automatically duplicating themselves. Each duplicate typically shares the qualities and capabilities of the original ring. While the thought of an unauthorized person getting a hold of a power ring and making duplicates for nefarious purposes, their ability to inflict damage is limited because each duplicate still requires to be recharged by a personal power battery.
- Emergency Beacon: A Green Lantern in distress can use his/her/its power ring as an emergency beacon. The alert can be directed to a Green Lantern's neighboring sector, or it can be a Corps-wide alert.
- Homing Beacon: A homing beacon in the power ring can lead one Green Lantern to another. This was one of the recent power ring upgrade features added by the Guardians of the Universe. The power ring can be ordered to disguise itself to elude power ring wielding trackers. Guy Gardner successfully escaped the Green Lantern Corps of Earth by willing the power ring to keep his location a secret. Most often ring wielders will allow the beacon to signal their location to others. The Green Lantern Corps of Earth found the remnants of the Green Lantern Corps of The Klyminade by tracking them through their power rings.
- Mind Alteration: Though the ethics of mind tampering may be debatable, sometimes it is necessary. As the power ring relies on thought and will to operate, mind tampering is not impossible. The real difficulty lies in properly applying the power. There lies a risk of catastrophic damage to the mind should mistakes be made. A ring wielder can use the power ring to erase portions of an individual's memories. To protect his secret identity as Hal Jordan, Green Lantern created a mental block in the mind of Major Disaster. Green Lanterns have used mind techniques as part of training. New recruits may be subjected to mind scans by other Green Lanterns or the Guardians of the Universe. They are taught to build mental defenses to protect themselves from psionic attack. The power ring can also be used to beam information from the ring wielder to another being. Green Lanterns have used this technique to share information regarding their enemies during combat situations.
- Pocket Dimension: Within the ring exists the possibility of an entire world. When Green Lantern Abin Sur of Ungara defeated the evil sorcerer Myrwhydden, he reduced the magician to submicroscopic size and imprisoned him inside the power ring within a world created by the Green Lantern's will. This undefined space may be a tesseract or a virtual reality created by the power ring. Whether or not this area exists in all rings has yet to be proven. Years after Abin Sur's death, Myrwhydden's power grew, allowing him to alter his environment and escape to battle the next Green Lantern, Hal Jordan. The power ring's interior appeared as a barren wasteland, dotted with dead trees and sea shells which Myrwhydden used during an escape attempt. A few years ago, Mywhydden was removed from the power ring to be sentenced to an Oan Sciencell.
- Resurrection: In rare cases, the ring can keep its user alive after his/her body reaches a state of irreversible death. In Driq's case, the Green Lantern was kept "alive" by his power ring's refusal to let his life slip away.
- Security Protocol: The rings can be programmed. They are coded to the wearer to make them unusable if stolen. The ring will refuse to take an action that would kill a being unless they are on Oa or with permission. The Guardians recently removed the lethal force prohibition, first to allow lethal force against members of the Sinestro Corps, then against all enemies of the Green Lantern Corps.
- Preset Conditions: Commands can be stored in the ring to be executed at a later date even if the bearer is not wearing the ring. This ability was demonstrated by Ch'p, who surrendered his ring but ordered it to restrain his enemy after a few moments had passed.
- Thought Relay: Otherwise known as a telepathic link. A Green Lantern can do the ring works at short distances, but its effectiveness is considerably lesser when compared with a user wearing it in his/her/its finger.
- The potential of the ring is determined by the will power of its user, which affects the intensity of powers, the volume of created objects, etc. The user must focus to keep all effects in use and must divide the energy between all these; For example, once Hal and Alan wanted to destroy a mystical prison that was holding the JLA and JSA together. They were using a portion of the energy of their rings to protect themselves against the rigors of space. They only were able to destroy the prison after deactivates their protector auras. Once, Lobo broke a bubble of energy created by G'nort due a bigger willpower. In contrast, if more people are holding a single power ring and focusing their wills through it in order to produce the same power, that desired power increases, or is easier to be produced. 
- Mental Instability Protocol: Drug use, neural interference, vertigo or other forms of mental incapacitation can render the wearer unable to use their ring, rendered useless.
- Yellow Impurity: Formerly, the rings were unable to directly affect yellow. Now, a wearer can bypass this if they can 'accept fear', which is personified by the color yellow. Rookie Lanterns are more susceptible to fear and thus vulnerable to the color yellow.
- Recharge Protocol: Formerly, the rings needed to be charged after a period of one planetary axial rotation (dependent on each ring's location), regardless of how often it was used. Currently, the rings retain a charge until they run out of power. This variability ensures that the wearer takes great effort to keep it charged. This weakness does not apply to Ion's host.
- Vibrational Interference: If a vibration from a device is set to a certain speed, it causes the ring to function only in miniature, so that if the user wanted to make hands to grab something, the hands would be too small to grab it. A clock has been seen to do this.
- Red Power Rings: Red Power Rings can dissolve the energy from a Green Power Ring.
- Although usually the rings require that their wearer be conscious for active usage, the Guardians have shown the ability to control them no matter what their regular user might be doing. In some cases, this means moving the Lantern in question without their consent or sometimes even knowledge.
- Appearances of Green Lantern Ring
- Item Gallery: Green Lantern Ring
- Images featuring Green Lantern Ring
Links and References
- Green Lantern (Volume 2) #90
- Green Lantern (Volume 2) #67
- Green Lantern (Volume 2) #166–168
- Green Lantern Corps (Volume 3) #20
- DC Comics Presents #26, at least in the Earth-One Universe.
- Hal Jordan and the Green Lantern Corps #44
- Justice League (Volume 4) #15
- Dark Nights: Death Metal Multiverse's End #1
- 52 #6
- The Brave and the Bold #59
- Green Lanterns #1
- Green Lantern (Volume 2) #194
- Justice League Annual (Volume 4) #1
- Green Lantern Corps #219
- Green Lantern (Volume 5) #16
- Green Lantern Corps #217
- Justice League of America #22
- Justice League International #18
- Showcase #100
- Action Comics #483, page 16
- Green Lantern Corps (Volume 2) #23