These are the three Spiritual Stones from The Legend of Zelda: Ocarina of time (Kokiri's Emerald, Goron's Ruby, and Zora's Sapphire).
I made them because I couldn't find any good models of the stones online anywhere - none of them looked accurate. These were ripped straight from the game with the 1964 emulator, the VRML plugin, and Blender. They were then cleaned up in Solidworks to fill in missing surfaces, knit them into a solid, and orient them to print well.
Each Spiritual Stone has the stone and its holder.
The stones are simple enough that they can be printed with no support material. For prettiest results, print them with one shell and no infill, in a translucent color.
The holders are a bit more complicated. I've included models with integrated support that work great on my Replicator 2, but if you want to use your printer's own support generation, I've also added models without it.
For Kokiri's Emerald, print one stone and one holder. When assembling it, the emerald has a particular orientation. It's a bit confusing, so I've included a picture that should help.
The Goron's Ruby is easiest. One stone, one holder. They should slide together pretty snugly, but if not, a dab of super glue on the bottom should help.
Zora's Sapphire is the most annoying. Print three of the stones, three of the little accent gems (in the same color as the holder), and one holder. Use a clear glue to carefully glue the gems in their respective areas. You might need to use an exacto knife to trim the tabs a bit and make them fit well.
In addition to the stones, I made a base that they can be mounted on. A bit of hot glue works well for this (and if you want to take them off later, rubbing alcohol makes it lose its adhesion).