Gemsonas yaaaaaaaaaaaaaaaaaaaaaaaaay

Ok. So what I'm thinking is they used to be a research team from Homeworld.
Onyx was sort of the ring leader and the strategist.
Onyx gem is 'football' shaped and has a line in the center, making it look almost like an eye... Because it kinda is her left eye.
Her biggest ability is similar to Sapphire's futuresight. Instead of looking into the future and all its' possibilities however, Onyx has a limited 'field of view' in her present surroundings.
In a 75 km radius around her in all directions she has an all seeing eye. She however has to pause and think much like Garnet does for future sight.
In a shorter distance she doesn't need to focus as much however, and can be used to counter enemies movements when obscured from visibility.
Her weapon is a long rifle, which she's able to pick up and aim accurately with one arm.
Onyx tends to be a bit cocky, often getting her into little scuffles with Cinnabar, whom she is easily able to counteract. She does however really care about her two teammates and will do anything to keep them out of trouble. She's probably been poofed a bunch of times due to Cinnabar. She tends to hold grudges for a while, and if she's angry at someone she keeps them in her range and spies on them.

Now we go to Cinnabar.
Her gem is a reddish orange rectangular gem upon her forehead, just below her hairline.
Cinnabar is the team's demolition expert, skilled in most forms of explosives, primitive and gemtech.
This is fitting due to her pyromancy, allowing her to control any lit fire. (Which sucks if she has to fight under water)
She's the 'middle child' of the group, and is often finding herself in a lot of trouble due to her explosive temper and fiery personality in general. She'll never turn down a challenge, and it's partially due to her insecurity with her powers. She finds them worthless and destructive at times, and it's worse when her teammates get caught in the crossfire. She is incredibly passionate, and often goes to great lengths to prove said passion. She and Coral have a bit of a romance going on, but they haven't taken it to the level of Garnet yet and become Sunstone permanently. Mostly due to Cinnabar still being a tad immature and rash, causing her to hurt Corals feelings sometimes.
She utilizes a Naginata in battle, often using it for charges and throwing, but she is able to wield two if she needs the extra blade in a fight.

Next we have the Tech and Research Specialist, Coral.
Coral is the second youngest of the four and the second tallest. Ranging between Garnet and Pearl's heights.
Anyways, Coral is gifted with quick regeneration. To the point of replacing a lost limb, and staying in physical form when other gems may have poofed. Her regeneration CAN fix cracks in her gem, but it's a slow and painful (And sometimes very weird) process.
She has three sets of arms, all of which can be replaced, either by regeneration of one or simply attaching a new one, being a tech gem. She only uses one set however, unless she needs to fight with all six of her weapons.
She's able to use most technology, gem or otherwise, and is really smart to boot. She'd make an excellent strategist, but leaves it to Onyx since she's too nervous to lead.
She's the most emotionally imbalanced of the group. She's normally nervous and anxious, but sometimes she reacts to stressors in multiple ways. From getting furious to frightened or saddened. She is able to calm herself, but often has no time or is interupted. She's one of those people who doesn't stop working once she's set on something though. Often worrying Onyx and Cinnabar, due to the fact she's wearing herself out.
Her gem is a small circle located on the back of her neck, just below her skull.
She also fights using tessen that resemble shells in shape.

I'll type up Heliotrope later. She is the muscle though. But for now, fusions!

Now for Sunstone.
A master combination of Coral's precision and agility with Cinnabar's strength and tenacity.
Sunstone is about the height of Opal.
Her gems are a magnificent reddish orange, the combining of Coral's light orange and Cinnabar's deep red. Located in the same places as the unfused pair.
She maintains both Cinnabar's pyrokinetics and Coral's regeneration. Due to the combined strength of the two, she can also produce flames.
In this form she uses all six arms regularly, as opposed to Coral's common use of two. With these she wields a set of 3 Monk's spades, though it is possible for her to use 6.
The Monk's spades are a combination of Cinnabar's halberd's forming the crescent blade and staff and Coral's tessen as the spade.
She is rather emotional, but has a lot of passion and drive. She is a bit of a perfectionist, a trait she earned from Coral, which leads to her repeating training over and over until she gets it perfectly done if she stays fused for an extended period. (Longest 'current' I'd say is approximately a week.) She's not as aggressive as Cinnabar, but she isn't as anxious as Coral. In fact she's pretty open and comparatively more fun to be around than the two seperate. However, due to the scientific nature of the team they don't care as much about fun as they do results, and as such they need to seperate when they need to complete tasks that only one of the gems can do seperately. Also due to Cinnabar being a tad hurtful at times it can cause Coral to want to seperate. They will get over it eventually, the two just need to round out the rough edges in their relationship.
Oh yeah she also has four eyes. Similar to Rainbow Quartz's. However they are all a vibrant reddish orange with pupils
The top set are under a visor like coral's

Next is Pyrope.
She stands at about Garnet's height. (Funny cause Pyrope is a type of Garnet :V)
She is a combination of Onyx's accuracy and timing with Cinnabar's strength and durability.
Her gems are a dark red. Again located in the same places as the unfused.
She has three eyes, though technically it could be counted as four. (The gem eye) The bottom two in a normal eye location, the top two located in the middle of the forehead vertically.
She has four arms, all four coming from her shoulders.
She has Cinnabar's pyrokinetics and Onyx's all seing vision. However the distance increased to a 150 km radius but she can't produce flame like sunstone.
She wields a harpoon gun. Using Cinnabar's halberd as a spear and the ribbon attached to the end as a chain to connect the projectile to the gun.
Pyrope has been noted to be the opposite of sunstone emotionally. Cold and silent usually, she lets her actions do her talking. She is very mission driven, and a little bit condescending to others. Strangely enough including Coral. This of course makes the two separated upset, but they require her for certain missions. She is the more shortlived of the fusions they have, as they do not wish to hurt Coral emotionally (Or physically if she gets in the way of a mission).
When she talks, it's a stinging condescending tone often. Compared to Sunstone's giddy, albeit slightly geeky, tone.


Next is Tiger's Eye.
A skilled combination of the accuracy and timing of Onyx and the precision and agility of Coral.
Tiger's eye is somewhere between the other two dual gem fusions of the group.
Her gems are black with orange striped into them.
She has six arms, but no legs, producing a fusion similar to Malachite in build.
She has eyes similar to Pyrope's, and lack the visor that sunstone has. Her eyes are also all mismatched.
A black iris (Top right), a bright orange iris (top left), and a brown iris with a gem eye.
She utilizes a pair of crossbows.
Tiger's eye is a bit of a tricky one. Her emotions vary much like Corals, but mostly in the negative spectrum due to Onyx being a bit of a pessimist. She is however an excellent hunter, and is often used when they require a specimen from a planet that the two alone or cinnabar can't capture.
She has both powers of the original two, but no significant boosts are apparent. They are however more proficient with their use in the powers. As both gems are excellent strategists they can often come up with wonderful plans that usually end in success.
The word usually is used rather than always, since sometimes Cinnabar gets a little jelly and sabotages the mission. Causing Onyx to get angry and Coral to get a little guilty/sad. The resulting emotions cause them to split, as Coral knows she and Cinnabar have strong feelings together which in turn makes Onyx a little more angry. In which case she goes off to vent after splitting.

The last one I know what the gem is gonna be. But not much of the personality.
She's gonna be Iron Pyrite. The gang calls her Fool's Gold though, cause two syllables is easier than four. The gem is gonna be gold with a black outline inside the gem. Similar to iron pyrite in rock.

Heliotropes fusions haven't even been thought up yet.