I haven't seen the episode again that showed the "watermelon" colored crystal type gem. What kind of mineral/gem was it that Kristen had made into a pendant for a necklace that appraised at $25,000?

Wow I don't remember any show where she found something that apprasied for $25,000. However, I think the show you are refering to is the one on Tourmaline. She did find some watermelon colored tourmaline and had a necklace made out of a piece of the multicolored gemstone. But I think the apraised value was $12,000. Still a pretty penny for sure. Maybe this is the show you are thinking about.