It's not Blue and White, which would be larger, brighter blue above and cleaner white below with a clearly marked blue breast.
This is similar to the recent male Blue-throated in Tai Po Kau, and looks like a male klossi Blue-throated. The sudden increase in records of these locally is intriguing - could it be the result of more people looking, is this species becoming commoner (either in the wild or in trade, if these are escapes) or have we been mis-IDing a stage of moult in Hainan Blue?