Okay, something has been bothering me ever since "On the Run": Gems reproduce by travelling to new worlds and "harvesting" gemstones to create new gems. The process then repeats itself as more gems are created to travel to more planets and harvest other gems. There's one problem with this process though: How did it start? There must have been gems around to invent the technology neccessary for space travel and the machines to mine planets for gems. They could not have been grown in kindergartens themselves, as the technology did not exist yet. So where did they come from?
Here's my theory: The first gems evolved from sea creatures that produce organic gemstones (pearls, coral, etc.). Over time they evolved in such a way that the creature's life force passed into the stone itself, eventually creating pearls that were self-aware and could manipulate the world around them. Soon they developed the ability to project bodies made out of energy and became intelligent enough to build their own civilization, with new generations being born from the sea to replace the old ones as they died out. After thousands of years they began experimenting with inorganic gemstones and discovered that they could induce the same process artificially. They most likely used this process to create gems to fill jobs that Pearls did not want to do (workers, soldiers, etc.). However, one of the artificial gems became too powerful (let's say Blue Diamond) and led a revolt against the Pearls. When they won, the Diamonds became the new rulers of the planet, with other precious stones as the upper class and common gemstones (quartzes) as the lower class.
Soon, the gems realized that the process to create new gems drained the life from the environment around them and could have catastrophic consequences if it was allowed to continue. Plus, they were probably beginning to run out of readily available gemstones, so the gems began the process of mining new planets for gemstones.
So yeah, that's my weird tangent based on Jasper's offhand comment about Pearl.
This isn't so much a theory but I'll weigh in. For me there is a lot of sudo-hindu mythology aparent in the show. Not just the crystals and their spiritua/magical uses, ot the four and six armed ladies, I also see references to chakra and hindu spiritual beliefs in the series.
My thought is that the statue was originally a single fusion gem and was the original home of the original gems who came to earth thousands of years ago, and for a time became recognised and worshiped as a god on this world (kicking off hindu mythology) The fusion gem consisted of fourteen gems, one for each of the primary chakra. For thousands of years the gems ruled humans until the political split happened over whether or not to classify organic life as equal to gem life (humans being the most advanced organic life they'd ever met, and the majority of sentient life in the galaxy being mineral based)
Until that war there had likely only ever been a limited number of Gems. Reproduction had never been necessary because they live forever, this resulted in the birth of the kindergarten as the gems who treated humans as 'a lesser specie' sought to increase their numbers, overcome the seperatists and cull the human herds. The seperatists fought, and even used the statue to fight off the new gems, but lost many of their numbers.
Most of the gems now are not in fact the original gems from the start of the war. Many of them were bred just for the war, and only a few original gems remain. Rose Quartz gem (in steven) being one of them. But the statue, the first gem, the Original fusion who once represented wisdom, power, honor, respect and became the origin of what we now consider hindu mythology, still waits, Innert, for it's children to come home :)
My prediction is that at some point during the series they are going to have to revive the statue, and it can't be done by just the five gems present. It will take a gem in each room meaning they will have to win over other gems along the way.
Honestly, I've always had a problem with the "gems don't reproduce because they're immortal" argument. Yes, they cannot die of old age, but as Amethyst demonstrated in "Indirect Kiss" accidents can still happen. Since healing powers are apperantly really rare, I'm sure many gems shatter and are never revived again. On top of that, gems are in danger of being destroyed by other gems, especially if Jasper and Peridot's attitudes are typical. Plus, they had to originate somehow.
I do really like the idea of the giant hindu goddess fusion, although I feel like a 14-gem fusion would be way bigger than the temple. There is also the question of why she only has eight arms, although Garnet proves that fusions do not always add up the arms of the component gems.
yeah, after I posted the comment I thought to myself that fourteen gems might be a bit much. A large portion of that depends on whether you go with modern interpretation or classical interpretation of the chakra. The chakra are actually defined as spear point, seven spears of energy that go through the body, resulting in fourteen energy hotspots on the outside of the body. In classical mythology they were treated as 14 chakra but modern just says seven chakra, but thats not including a whole heap of minor chakra and .... it just gets complicated. The theory would still work with seven chakra and the statue is easily the right size for a seven gem fusion.
And what you said about gems shattering is part of the reason I think reproduction is new. I get the impression that before the civil war started it was rare to need to reproduce. The kindergarten was clearly invented tech and not natural, but if gems could naturally reproduce then why would Rose have to give her gem to Steven? It would have been a new gem if they could reproduce naturally.