Well, I know I'm not responsible for fusions (that's Kronshi's job), but while working on Talc's design I had a few ideas, so I'll just drop it off and see if y'all are okay with it? 

Um, since Amber is fossilized tree sap, and Evenkite is often found in fossilized trees, maybe they could make Petrified Wood together? Eeeeeep, it was a thought.

Another idea was for Emerald and Aquamarine. Since they're both varieties of Beryl, and water is often tinted green or blue while it is actually colourless, I was thinking maybe Gohesnite for their fusion? It's a nearly clear variety of Beryl but can take on tints of their surrounds as well, most commonly blue and green, and a lot of it's symbolic and metaphysical traits are shared between Emerald and Aquamarine.

Finally, for Black Zircon and White Spinel, I was thinking of Onyx? All three of the stones are formed due to heat from lava and magma, and Onyx is coloured both black and white.

I have no idea, just wanted to drop that in. Feel free to ignore it. XD