Rainbow Daytona is the name people use for a Rolex Daytona whose bezel is set with a row of colored stones. The stones are the part you check. The rest of the watch is still a Daytona case, a Daytona bracelet, and a chronograph movement.
How it differs
A steel Daytona with a printed tachymeter is not this watch. Here the bezel is a gem-set ring. The colors run around the circle. Stones fall out, sit crooked, or get replaced one at a time, so the row is the thing to describe. Do not grade the stones. Say whether they are present, whether they match in size, and whether the metal around them is torn.
The dial may be light or dark. The panda arrangement, light dial and dark counters, is a separate nickname. If this watch has that dial, say so, and still treat the bezel as the reason for the rainbow name.
Common mods
Bracelet changes happen on these watches too. The end links still have to meet the case. A bright bezel does not excuse a crooked end link. Crystal changes happen when a stone or a bump marks the glass. The crystal must clear the chronograph hand. Movement work is the same chronograph check as any Daytona: start, stop, and reset. A stone that was reset after a loss should sit at the same height as its neighbors.
What to check on a used piece
On a used Rainbow Daytona, check the bracelet end links where they meet the case, the crystal over the dial, and the movement. Then turn the watch under a lamp and count the bezel stones you can see. Missing seats are a bezel note. They are not a reason to invent a story about the movement.
The notes for those parts are the bracelet, the case, and the movement.