NOTE: This article contains spoilers! Read with caution.
According to various legends in the series, the planet on which the story takes place (presumably Earth) was visited by six meteors, which broke the planet six times, creating six new moons. While it can be assumed that the Lunarians reside on the original moon, this has not been explicitly stated. It does not appear that anything lives on the other six moons, as Aechmea was able to build a home for Cairngorm for complete isolation on another moon.
The Lunarians are the spirits of humans who have remained trapped in this existence since they cannot pass onto the next world. Prince Aechmea implies that the Moon is where unpurified souls eventually wander to until they can be cleansed with prayer and move on. He states that the Lunarians have been trying to pass on for tens of thousands of years, though presumably souls have resided on the Moon while humans and other animals still existed far before that as well. On the Moon, they have built a small civilization consisting of at least one town-like structure where they reside. This structure contains many facilities such as factories, gardens, laboratories, and places to dine.
For thousands of years, the Lunarians have travelled to the Land to attack and kidnap Gems. At first, they tried to persuade the Gems to cooperate but that did not work so eventually they decided to grind all captured Gems to dust and spread them over the surface of the Moon. They plan to do this for a very long time until the Moon shines with the Gem's shards. They have also kidnapped all of the Admirabilis and use them as cattle. Larger Admirabilis can be seen grazing on the Moon's surface, eating up sand to build their shells.
At some point later in the story, Phosphophyllite infiltrated the Moon by letting themselves be captured. They were able to learn about the Moon and the history of the Lunarians. They made an agreement with Prince Aechmea to bring more Gems back to the Moon in return for the attacks to stop and for the revival of the previously captured Gems.
The Moon consists of mostly barren land dotted with craters. Deep below the surface exist the oils and metals that the Lunarians extract to create their structures. The top level of the Moon is fine dust or sand of gemstones, created by the Lunarians when a captured Gem is ground up and scattered across the surface. It's unknown how thick this layer is, but the Lunarians had expressed desire to continue building it up, up until Phosphophyllite arrived on the Moon. The Admirabilis can be seen feasting on the sand. The atmosphere is described to be too harsh for lower hardness gems to be last on.
Although there is no specific name for the Lunarian settlement, the Moon contains a large city like structure that the Lunarians reside in. The building appears to be one structure rather than smaller ones separated, and are boxed in within its confines with four walls. The structure is built out of oils and other materials that are found on the Moon, and are constantly changing each day by melting away and reordering into a new structure. The only consistency appears to be the design of it. The Lunarian structure is highly geometric and generally has 90° angles with layering. The only curved features are smaller ornaments that are symmetrical along the y-axis. The designs of the structure resemble hopper crystals, which are most often associated with bismuth crystals, a synthetic version of the element bismuth that grows in spirals, but on flat 90° angles rather than a constant curvature.
It's unknown how large or long the single structure is.
The style of the structures is most likely in contrast of the organic like structures found on Earth with the Gems, simulating synthetic and artificial as these shapes are hardly ever found in nature. It's also possibly based on minimalistic architecture that often incorporates flat planes of design which became popular during the mid 20th century.
The Lunarians hill changes everyday so some locations may not be permanent. Others are implied to have existed for longer periods of time. Note that most of these places are not explicitly named in the series so the names used in this article are for the sake of organization and convenience.
At one end of the hill, the road extends out into a large platform. Here is where the Lunarians disembark and travel to and from the Land. When leaving, the Lunarians adopt the appearance that they are mostly seen with when emerging as sunspots. A large figure stands in the middle with many normal-sized sundries surrounding it. They are then covered in a cloud that is revealed to be both a device for transportation as well as cloaking. The appearance of the sunspots as seen from the Land is in fact this device opening up.
When Aechmea was explaining their people's history to Phosphophyllite, they sat in various locations where they were served food and drinks, including alcoholic beverages. At first, they both ascended a stairway to a dining room with an elegant table set by a large window. After eating here, they moved on to an open area where they sat by a counter. Here, Aechmea indulged in several alcoholic beverages.
The Synthetic Gem Factory
This facility is a large space filled with spheres either suspended or lifted by pillars. Here is where synthetic gems are produced from minerals found on the Moon using heat and pressure. Within the spheres, eight kinds of metals and carbon undergo high temperatures and pressures to create various gems, including diamonds, corundum, and beryl. On the ground floor, the synthetic materials are processed into tools, weapons, or shaped into artificial Gems.
The Synthetic Human Factory
The Lunarians also have a experimental facility meant to create synthetic humans, presumably so that they can pray and purify the spirits and allow them to pass on although it's not stated. It is mostly shown to be a large tank of liquid with moving white strands called "human particles". There is apparently a strange music that plays in this place. Both Phos and Semi did not feel comfortable being here. It was shown in Chapter 56: Synthetic Pearl, but is never mentioned again.
Gem housing is a place built for the Gems that have decided to reside on the Moon. They do not melt at night and tend to remain the same. It features bedrooms, elevators, and a large Atrium with sitting area and a television to display announcements, as well as a front desk with Lunarians to serve the Gems. The furniture and features more resemble the exterior of the Lunarian structures with the angular and geometric styles. The bedrooms and there furniture are quite large in scale, and one wall is open to the Atrium and one wall facing the outside. The atrium is very large, and mainly consists of a pool with various waterfalls coming from above into it. There are bridges over the water to the centre of the pool where a seating area is.
A building that New Goshenite has been in (and has presumably been the only one), where Lunarians interested in skateboarding gather. The Lunarians there taught New Goshenite how to skateboard. They presumably own the half pipe and ramps New Goshenite is later seen using.
Despite being on the Moon, there exists an unnamed garden with a large amount of foliage and plants. Aechmea can be found here and enjoys relaxing in this area. Later on the Gems have occasional meetings with Aechmea here.
Gem Restoration Area
A large area housing individual machines that are meant to restore Gems that have been ground into dust on the Moon. This area is currently inactive.
Fashion Designer Office
A space used by the two fashion designers, Quieta and an unnamed student Lunarian. There are tables and other tools, as well as fabric, in order to create clothing. There is also a large board in the middle of the room with papers of the proposed outfit designs.
- The Lunarians - The Moon is their home until they can find a way to purify themselves and pass on. Among the Lunarians, there are a few notable individuals:
- Aechmea - The leader of the Lunarians, he is adored by them all in the same way all the Gems love Kongo-sensei. They affectionately call him "Prince" as he does not like using his own name.
- Semi - A big and muscular Moon Person who acted as Phos' guide and monitor. They are shown to possess a demon-like battle form when on the Land.
- Appe - Semi's twin.
- Barbata - The Moon Person who is in charge of the synthetic Gem factory. They explained to Phos how the factory works.
- Quieta - One of the two fashion designers, the lead and who has designed Cairngorm's outfits.
- The Admirabilis - A species that was kidnapped by the Lunarians for their beautiful shells. They are currently kept as cattle and can be seen wandering all around the surface of the Moon and the hill.
- The Gems - Though technically in suspended animation, all the kidnapped Gems have been ground to dust and spread over the Moon's surface. As part of the deal with Phos, Aechmea says they will try to restore them, but it may take the entirety of their lives.