The second Spiritual Stone from "Ocarina of Time", also known as Goron's Ruby.
I've planned to make it on Juny 22nd - the longest day of the year, but I think the middle of the Summer fits fire element too...
Kokiri's Emerald - [link]
Zora's Sapphire - [link]
The templates I used: [link]
The Legend of Zelda (c) Nintendo