This pocket watch uses the highest level of enameling of the era. The recipe for blue enamel was once a trade secret, and the most transparent blue color could only be produced by firing at a specific temperature. In those days, there was no temperature monitoring equipment and the enameller had to rely on his experience to determine the temperature of the fire, such as spitting to see how fast the spit would evaporate; enameling was a skill that relied heavily on experience and intuition.
Blue background with gold was the color palette of the French royal family, and the fleur-de-lys was a symbol of the French royal family. The blue background with gold fleur-de-lys on the pocket watch case suggests that this may have been a watch used by French royalty.