Very Similar to Diamond
Unicorn is very like Diamond. They have almost the same gold-tinted, warm sparkle color. What's different about the two is the gel color. They may both be transparent, but Diamond's gel is ever so faintly orange-pink, whereas Unicorn's gel is slightly darker and greenish. It's extremely subtle.
Is this different enough to make the purchase worth it if you already have Diamond? I suppose it depends on your project. I have all the clear Stickles and use each them for very different things. Unicorn will be no exception.
I know this sounds like a negative review, but I just want to be thorough in my description. It's beautiful and will go great on just about anything. Not at all what I expected when I ordered it, but I love it nonetheless.