Sapphires, in general, are a variety of corundum found at or near bedrock. They are a gem favored by many for their blue sheen, but there are also other varieties and other colors to be had. Rarest and most desired of these varieties are the star sapphires.

In Revaliir, star sapphires grow deep underground and have many uses other than decoration. They are very effective focal points, for example, and typically function as nexii of power for synthesis items. Their presence is essential for items like the radiant saber to channel its blade of light, so star sapphires are desired by noble and mage alike.

Currently, the largest mine for star sapphires in all of Revaliir is the bowels of Vada Valley, where the roots of the crystal spire that grow next to lava pits seem to provide an endless supply. However, that mine is also dangerous to brave, thanks to its presence outside of the spire's protective monoliths; so most looking for star sapphires go to the Tori Mountains between Ataiyo and Railoch, the dwarves in Baltil, or the drow in the Umbral Depths. There are also some infamous smuggling operations on Apoy Island where unauthorized mining takes place against the native's wishes, though anyone buying from those ne'er-do-wells best not have any issues of conscience about what it took to get their gems.

For those not wishing to brave the mines or smugglers, prospective buyers can still find star sapphires at major markets around the world. They are considerably rarer in those conditions, of course, so shoppers should beware of fake gems. A fake star sapphire can look very similar, but it will blow up if tried to use in place of a true gem. It is often better to go directly to the source for anyone needing this particular kind of sapphire, or to contact a trusted gemologist to verify a product before purchase.

-From "The Basics of Gemology: A Study"