has:yellow-starhas:red-banghas:green-checkFinds messages carrying a star or icon of a specific color.
has: accepts stars (yellow-star, orange-star, red-star, purple-star, blue-star, green-star) and icons (red-bang, orange-guillemet, yellow-bang, green-check, blue-info, purple-question).
has:yellow-starOpen in Gmail ↗Messages with a yellow star.
has:yellow-star OR has:purple-questionOpen in Gmail ↗Yellow star or purple question mark.