blue and yellow were born when white cast away all of her cyan and yellow light, as well as one of her two pairs of arms. blue diamond's left arm belonged to white, just like yellow's right arm did.
for blue i wanted to go with a more heavy, somber, draped look while trying to lean into the water theme i gave her, hence her lines, like the ripple of water. as yellow is in charge of most of the gem army, i wanted to give her an outfit that really made her feel more militarian. all of my diamonds have six fingers (but i draw four fingered hands)