A cocktail grapefruit, as it turns out, is no grapefruit at all. It only looks like one. It's a little smaller than some grapefruit, though, as you can see from the photo above. (My hands are pretty small.) The cocktail grapefruit is actually a blend of a mandarin and a pummelo (or pomelo). The pomelo side presumably gives it that yellow and green color and thick skin, while the mandarin side of its heritage makes it much sweeter than a grapefruit.
We split ours open to see what it looked like. It was bright yellow inside, with two or three large seeds in each segment. It was deliciously juicy; we dripped juice all over the kitchen just trying to peel the thing. The taste was very refreshing, too; it had the tart brightness of grapefruit but none of the sourness. It was sweet, bright, and very juicy. We enjoyed this one a lot. Have you ever tried it? Related: Farmers' Market Report: Citrus Everywhere ... ALSO see: Recipe: Broiled Grapefruit (Images: Faith Durand)