Regarding the popularity of cloisonné enamel WT, I think the reasons include:
1. Rarity. The production volume is limited by the small number of artisans capable of making the dial
2. Every 5131, 5231 is unique, due to individual variation of emamel
3. The aesthetic effect of the dial is truely appealing, with layering of colours. As if your are having a miniature globe on your wrist.
I am sure that you will be delighted by your 5231J
Cheers,
Henry