Yellow Diamond and Pink Diamond to scale, based on their Pearls, because I saw way too many pieces of fanart depicting PD as downright tiny compared to Yellow and/or Blue Diamonds.
The example you’re using is from Message Received, Yellow Diamond’s first appearance, where she’s much smaller than her later appearances. (In the image above her Pearl goes up to her knee, but later Pearl barely goes up to her ankle.) A more accurate height chart would be this:
Emma's Blog 