Peridot and Amethyst together in a fusion would be called Ametrine. My reasoning is below.

-For those engaged in what may be considered mundane activities, Ametrine teaches one to balance physical activities with one's spiritual hunger. Workaholics(Peridot) learn to pause and enjoy the fruits that one's labors provide. (Amethyst's contribution)
Procrastinators(Amethyst) discover the empowering joy of fully completing a task and the rewards one reaps when a goal is finally achieved. (Peridot's contribution) Those that walk among the clouds suddenly find purpose in touching the Earth.
If one walks with fear, Ametrine will reveal the hidden warrior within. If one moves with detailed precision, executing well thought out plans, Ametrine will reveal the power of serendipity and the joy from taking a chance.

Below are slight spoilers!

If you watched "Too Far" already you will know what I'm talking about!

Ametrine energies are said to stimulate the intellect and rid the aura of negative energy.
Ametrine will help one recognize the divinity within all, thus eliminating prejudice.( Peridot holds prejudice against Garnet for being a fusion, Pearl for being a servant, and Amethyst for being a runt. Amethyst fusing with her would eliminate those feelings and thoughts.)