Sequinoans. This strange race of Amazonians has many unusual traits, but the foremost our scholars are concerned with are their gems. You see, Sequinoans somehow form gems naturally, perfectly smooth and colorful gems that resemble cut opals in shape and a mix of paint swirled together in color.
The question is, how do they form these gems? This ability clearly concerns magic, but at the same time, it must have a biological basis to exist.....so how are the Sequinoans making gems like this?
Sequinoans start forming these gems when they start puberty, and until then they have a gem-shaped niche, lined with pink skin, below the collarbone and above the breasts (where a locket would normally hang). When the time comes, this niche will start secreting a strange fluid which wells up and hardens like amber, forming a gem. And if removed (see below), the Sequinoan will form another gem.
As our scholars interacted with the Sequinoans, they found that these gems can be painlessly removed by the owner when they feel like gifting one, that they are practically indestructible (taking hits from steel weapons or fallen rocks without even a scratch), and that they glow when a Sequinoan is agitated or exerting a lot of energy, as in combat, as well as when exposed to energy sources like an electric battery. In fact, from what we've seen, touching a gem after it's been exposed to electricity will result in quite the shock!
When a Sequinoan is seriously wounded, enough to induce the development of a scar, the wound will produce new skin cells, pale pink ones, which will then form a gem within the scar. Smaller wounds, however, do not form gems and heal as normal-for us, that is.
The Best Answer Will.....
Take into account the above traits to explain this unusual ability; ie. how Sequinoans create gems with these properties. This answer can include magic but should be based in biology and natural selection, with little to no use of magic at best, much like the answers for this question.
Finally, let me know if changes are needed; I appreciate feedback!
The question suggested to be a duplicate of mine is about an organism forming a diamond, mine is not. It is about a specific species of humanoids forming a gem with specific properties, but is almost certainly not a diamond. I can certainly understand the confusion, but they are not the same question!