i don't think the praseolite exists in the cushion cut, i've been to several stores and have only seen them in citrine, yellow citrine and amethyst! the amethyst is beautiful in the cushion cut, the colour is very saturated and rich.
I agree, I've only seen the cushion cut in yellow gold, in citrine, yellow citrine and amethyst... I'm surprised the praseolite earrings and necklace aren't emerald cut as well. I guess this makes it a little different....