Amethyst

From Character Introduction:

On the left is the carefree Eighty-Four, on the right is the laid-back Thirty-Three.
No one really cares which is which anymore, including themselves.

Amethyst (アメシスト, Ameshisuto) are two twin Gems who mainly do patrol duty. They are individually named Eighty-Four (エイティーフォー, eitīfō) and Thirty-Three (サーティースリー, sātīsurī). They're two in one and partnered with each other. According to Yellow Diamond, twin Gems will not break when they touch each other, as demonstrated when the twins bash their heads together, much to the chagrin of their observers. They are both great at swordplay and were recommended to train Phos for a short time.

Appearance

Amethyst has a purple color scheme and wears either the winter or summer uniform depending on the season. They also wear standard black shoes and knee-high socks but no gloves. Their hair is long, braided and styled to cover one of their eyes. Initially, Eighty-Four covers their right eye, and Thirty-Three covers their left eye. They later switch, then Eighty-Four switches again to deceive Phosphophyllite and take Thirty-Three's place.

in most recent chapters, Amethyst Eighty-four changed their hair to a more symmetrical shape. Eighty-Four's hair is now parted down the middle with braided bangs that go to the back, with their short straight shoulder length hair underneath. Thirty-Three's remains the same.

Personality

The twins work in tandem for a lot of things, often talking at the same time or finishing each other's sentences. It seems that the two rely on each other, but one of them states that they wish to be more independent, since if the Lunarians were to come for them, they'd would both be taken away.

Thirty-Three was initially unsure about taking care of Phosphophyllite, but when Eighty-Four joined them, they both became confident. They are kind and a bit silly, sometimes teasing other Gems like Phos. Together, they seem like they can be occasionally cocky and confident in their abilities. However, they are very caring and tend to put others' well-being first.

Amethyst 84 has learned to become more of their own individual and they serve as an assistant scientist on the moon. They seem to be highly interested in more of the psychological aspects in the science field, and have addressed that on Earth, the Gems have never received the proper treatment for the amount of trauma they experience, noting it especially with Yellow Diamond who is the oldest and has been through the most.

Amethyst 33 has recently learned to cope with their twin leaving, and believes after 200 years that they are alright. They think 84 is doing alright as well, and still feels connected to them.

Story

The Amethyst twins are side characters though they have a few prominent roles in the story. They were first formally introduced when Kongo-sensei had Phosphophyllite team up with them in order to gain experience with swordplay. During patrols together, they teased Phos with their carefree attitude. When a sunspot finally appears before the trio, the twins wanted to show off their fighting prowess to Phos. They skillfully cut down many Lunarians, but became careless when the central Moon Person was revealed to be a new type with a teeth trap made from Sapphire. The twins were caught and shattered while Phos helplessly looked on, paralyzed with fear. Bort ran to the scene and defeated the trap, freeing the twins whose pieces were quickly collected by the other Gems. Later that night, after the Amethyst twins were reassembled by Rutile, they found Phos kneeling and bowing down, apologizing to the twins for their inability to act. The twins reassured Phos and apologized instead, claiming that it was their own boastfulness that made them careless.
When Phos gained new gold arms and became stronger, the roles of the previous incident were reversed and Phos showed off their new strength to the twins, easily handling a Sunspot and defeating the Lunarians. The twins became very impressed and hugged Phos, saying that the new, stronger Phos is nothing like the old one. After Shiro appears and was split into puppies, most of the Gems including the Amethyst twins spent the day hunting and collecting them. In the anime, both twins were shown chasing after the same puppy, causing them to bump into each other.
When Phos wanted to learn more about the Lunarians, they grabbed and held a Moon Person during an attack and tried to communicate with it. The Amethyst twins dispatched the rest and eventually defeated the one held by Phos as well, unaware of the younger Gem's intentions and believing Phos needed help. (In the anime, it was Cinnabar who defeated them.)
Much later, when Phos successfully infiltrated the Moon and returned, the Amethyst twins listened intently to their stories. While Eighty-Four slept,Thirty-Three expressed their concerns about both of them being so close together, as they would both be taken away by the Lunarians rather than having one be saved. Phos tempted the Gem into going to the Moon, both of them not knowing that the remaining twin was not truly asleep and heard everything. One of the twins ends up accompanying Phos to the Moon. At first, it appeared to be Thirty-Three, but it was in fact Eighty-Four masquerading as their twin in order to take their place on the Moon.
Eighty-Four travels to the Moon with Phos and the other Gems, and seems to be the one of the first ones to adjust well to the Moon and Lunarians. They are taught science under Barbata and seem to make it far in this aspect, even changing their hair and clothing style to reflect their new outlook.
Eighty-Four attends to Yellow Diamond when Yellow Diamond repeatedly wakes up and seems to be in hysterics. They express some level of wanting to become a Lunarian like some of the other Gems, and attempt to coax Cairngorm into getting information on it from Aechmea. This doesn't lead anywhere.
Eighty-Four is present upon Phos's return to the Moon.

Relationships

During the beginning, Amethyst Thirty-Three states that they never spoke much to Phos before the younger gem was ready for combat. They enjoyed teasing Phos, causing the younger Gem to become tense when stating that the place they're assigned to patrol is a common place for Lunarians to show. During patrol training, the twins would give false alarms to Phos by expressing astonishment at passing animals. However, they are very kind as well, often speaking in a soft, slow manner. When they were shattered by the Lunarians and Phos was unable to fight back, Phos asked for their forgiveness but they apologized instead and claimed it was their own fault for being careless and trying to show off. Later, when Phos gained their gold arms, the younger Gem fought the Lunarians single-handedly in front of the twins, causing the two to hug Phos in admiration.

Based on how other Gems treated each other, it can be assumed that Amethyst has a friendly relationship with the other Gems and also like and trust their sensei.

Gem Info

Mineral: Quartz
Chemistry: SiO₂
Color: Purple, violet

Amethyst is a violet variety of quartz, and owes its violet color to irradiation, iron impurities (in some cases in conjunction with transition element impurities), and the presence of trace elements, which result in complex crystal lattice substitutions. The hardness of the mineral is the same as quartz, thus it is suitable for use in jewelry. The name comes from the Ancient Greek ἀ a- ("not") and μέθυστοςméthystos ("intoxicated"), a reference to the belief that the stone protected its owner from drunkenness.

Amethyst is the birthstone for February and the gem for the 6th and 17th wedding anniversaries.

Trivia

In original Japanese version, Amethyst's nicknames are written as 'Eighty-Four' and 'Thirty-Three' as English words in katakana. The nicknames are a reference to Japan Law twinning, a type of gemstone twinning. Twinning is when separate gemstones grow conjoined together. This can happen in different patterns called Laws. The Japan Law is when twin gems are connected at an angle of 84˚33".