The more Gems within a fusion, the bigger the fusion becomes.

[Her pearl flickers and a hologram of herself and another larger gem fuse together in a graceful dance. Two glowing gems to represent two of them. And then, another much larger fusion comes into view, with three gems glowing on it. This one had wild long hair and four arms. That's right. Four arms. And the two of them become one giant being.

With eight arms. And much bigger than the last.]

Obviously, the more gems that come together, synchronized, the stronger it becomes.