And a refresher on watermarks for earlier Hong Kong (or for any other British colony with British Colonial and Crown Agents watermarks)....

Upper Left: Crown and C C (wmk 1)
Upper right: Crown and C A (wmk 2)
Lower left: Multiple Crown and C A (wmk 3)
Lower right: Multiple Crown and Script C A (wmk 4)
As mentioned, these stamps are either watermark 3 or 4 (Scott nomenclature).
It is important to establish the watermark if, for no other reason, that valuations can differ.
Hope this helps.
