Ruby Diamond

Ruby is the odd one out among the Diamond skins. The other three gems were Summer Gacha pulls, but Ruby came from the Red Gacha, which cost 250 Oni Tokens, in the same Update 27.1.

It is also listed as Rare, a step above the Uncommon rating of Diamond and its sibling skins. Different currency, different gacha, a higher rarity tag: collectors notice all of that.

Visually it is a recolor with its own effects, and the fruit fights exactly the same. If you are building a full Diamond gem set, we'd expect Ruby to need a separate search, since it never sat in the same pool as the other three.