Originally, the only source of gems was a gem formation deep underground called the Heart of Kairos. No one knows the origin of this gem formation, but some say it is the birthplace of Kairos and others say it was made from the ashes of Kairos's father, the great Infinity Dragon. The Heart of Kairos grows slowly over time, and gems mined from it contain time magic.
Gems contain time magic, which can allow objects such as eggs and habitats to leap instantly forward in time, or warp materials forward in time from the deep past to build habitats in an instant.
This magic is the most rigidly regulated of all forms of magic, because it is also the most powerful. Access to chronomancy is necessary to keep a park running smoothly, but if such power falls into the wrong hands it can be extremely dangerous. One regulation imposed is that gems grown on dragonsai plants cannot be used in one's own park.
In the wild, gemstone dragons can be bred year round, but in parks the magic is regulated so that only a couple species are available at once. Gemstone dragons in parks are also unable to breed, an ability they retain in their natural habitat of The Shimmering Isles. These are protected by the wizarding community against poachers who sell the dragons or eggs to evil wizards for the nefarious purposes.