Cluster Gems

"The Cluster" is a forced fusion of former Crystal Gems. It first appeared in "Keeping it Together". Ruby speculated that it was made as punishment for the rebellion, but this is unknown. It was supervised by Peridot, and made by means that are not fully known at the moment.

Appearance
The Cluster takes the form of limbs joined together to other appendages. The limbs are of mismatched colors, such as dark blue, rust, violet, olive green and dull yellow, indicating that they originally belonged to different gems. The other end has four feet which are colored to the 'fingers' but not the 'thumb'.

A giant variant of a Cluster appears to be comprised entirely of limbs conjoined together in a single body, wrapped in what looks like a dark grey cloth. At its core, the fusion is comprised of five different shattered Gem Shards that are physically fused together. It possesses four, large eyes. The Clusters' irises and visible Gem Shards are green, yellow, blue, and purple.

"Marble Madness"
The Cluster makes a semi-hidden cameo when Peridot is accessing the Facet Five Kindergarten control room.

"Jail Break"
When Peridot and Jasper are at Sapphire's prison cell, Peridot says to Jasper, "We can't leave yet! The whole point of coming here was to check on the Cluster!".

"Keeping it Together"
The appearance of the Cluster was so horrifying to Garnet that she became unstable to the point where she almost un-fused. Ruby believes the Cluster was created as punishment by Homeworld for the Rebellion. It was eventually "poofed" by Garnet and currently resides within one of her bubbles in the Burning Room with other Gems that have been turned into monsters through one way or another.

Trivia

 * The Clusters are the first and only forced fusion in the series.
 * The Cluster is the first fusion to never speak in the series (not counting the screams emitted by it), the second being Rainbow Quartz.
 * Coincidentally or not, if one excludes the Cluster's thumb (which is covered by a boot), it has a glove covering every finger but the middle, while Garnet has a glove covering only her middle finger.
 * The blue "leg" off to the left appears to have the same boots as Amethyst and Ruby.
 * The Cluster is straight up disturbing despite the fact that this is a children's show
 * The silhouettes of the Cluster members have traits similar to other Gems on the show, most obviously Pearl's "Pilot" hairstyle.
 * It should be noted that when the Gem fusion's body silhouette appears, each "body" seems to have a similar body type, and hair style, implying that the attempted forced fusion may have been somewhat successful, before they reformed into a limb-comprised hand.
 * When the Cluster's bubbled gem was sent back to the burning room, its gem reshaped itself to appear like the Centipeetle Mother's gem.
 * This was later confirmed to be an animation error by Matt Burnett on Twitter.
 * Each of The Cluster's eyes has one plica semilunaris on either side of itself.
 * The Cluster is the second fusion to consist of four or more Gems.
 * The first being Alexandrite.
 * The Cluster and Garnet's Gemstones share the same gem placement, both having their gems in the center of their palms.
 * In Keeping It Together, Peridot refers to the Cluster as a "fusion experiment".
 * The Cluster's musical theme, is a corrupted version of Garnet's song "Stronger Than You", sharing many instrumentals and melodies.

Cultural References

 * The Cluster bears many similarities to Frankenstein's monster from the Mary Shelley novel of the same name.
 * Both are made out of body parts of different deceased individuals, acquired via grave robbing.
 * They are unnatural creations which were created through scientific means.
 * Both are represented as tragic, yet horrifying figures.
 * The containers could possibly be a Xenomorph reference.

Gemology

 * A Cluster of gemstones is a result of gems that fuse together due to extensive pressure from being underground. In most cases clusters are usually fusions of the same gemstone, however, in very rare cases, it is possible for clusters to form from different gemstones.

Gemstone(s)
pt-br:Cluster