I have a used version of what I think is this stamp:

This is described by the seller as Scott# 52C.
This makes me wonder - what are Scott# 52, 52A and 52B?
What year was this stamp issued?
And what is the Stanley Gibbons number?
The reason I ask is because, if I read Gibbons correctly, this stamp was issued in 1865 and is worth more used than mint - a lot more.
The idea that the stamp was issued in 1865 is supported by the following website:
http://www.linns.com/howto/refreshe...rcourse.aspxThis site has a picture, with the caption: 'Figure 4. A 5¢ blue King Kamehameha V stamp, Scott 32, from the Royal Portrait series of Banknote stamps.'
However, this stamp shown above is 52C and it's described by a number of sellers as having been issued in 1890.
So were there two (apparently) identical issues, one is 1865 and another in 1890, Scott# 32 and 52?
So in a nutshell: I'M CONFUSED.

Is there a perf or watermark difference? Because they look exactly the same to me!