Gemicorns are unicorns that have gemstones/minerals in place of their hooves, horns and bones.

Most gemicorns only have their gemstone horns and hooves visiable. But sometimes there are gemmies with "mineral beauty marks" that show up on there skin. These beauty marks are seen as a blessing and a curse.
Sometimes the beauty marks are malignant and form mineral over growths. If not treated, the mineral over growths well lock joints, over take limbs, immobilize and then eventually kill the gemmie.

Gemmies come in all different minerals, the some of the most common are of the quartz, fluorite, garnet species. The general rule is the more rare the mineral, the more rare the gemmie.
Gemmies who are lower on the Mohz scale (Fluorite, Apatite etc) need to be careful as their minerals are prone to breaking. Gemmies around 5 and lower often have chipped hooves, horns and are pron to fractures.
Any Gemmi that is made of Talc, Gypsum or other very soft mineral never survive and usually end in miscarriage or die during birth.
A Gemmies mineral isn't determined by genetics. Ex. A Diamond Gemmie and a Topaz Gemmie can have a Quartz and Schrol child. What mineral a gemmie has seems to be completely random.
Gemmies can have more than one mineral, usually in twos with one being the dominant. Gemmies with up to 5 and 7 minerals have been known, but are extremely rare.
When a gemmie dies, it is tradition that their family and friends carve jewelry/cut gemstones out of their remains. What is taken from them is worn as a way to always have their loved ones with them.
Because of this, gemmie families often have large collections of gems and jewelry that is passed down generation to generation, plus gemmies personal collections.

That's all I have for now, proly gonna ad in more. Feel free to ask any questions!