Ray -
My opinion is that there has to be nothing in the upper left corner to be a #52. If there is something there, like you said, then it is a #61. The Chinese character in the upper left takes on many different variations. I think your stamp has a partial Chinese character there, making it a #61.
Also, Hong Kong #61 is a prime example of green "fugitive" ink. Sorry to say, but your stamp has been put in water and is faded out. I scanned a pair of #61 stamps, from my collection, below to show you what the color should look like.
Your stamp does have an interesting purple security marking across it. I wonder if you can make it out, stamp in hand, under magnification? Just curious what company name is on it.
Hope this helps you,
Linus
