difference between 2 HK 15c stamps

[halfgweilo]

I wonder if anyone on the board can tell me the difference between the two 15¢ Hong Kong stamps, issued in 1973 and 1975. Sorry but I don't have the S/g # on both the said stamps. Both are definative sets. Many thanks.. Tom 

[kopenhagen5]

1973 - https://www.ebay.com/itm/1973-Hong-Kong-First-Day-Cover-FDC-Definitive-Stamps-15c-Stamp-/13307311610...

1975 - https://www.ebay.co.uk/itm/Hong-Kong-1975-15c-stamp-yellow-green-SG312-MNH-CS216-/264499485508

On a quick search it appears as though these were released 1973 - 1978 so perhaps no difference.

But I am only going by what I found on the internet.

[joztamps · Accepted solution]

It may be the watermark, and/or the paper.

One on-line catalogue describes the 75 set as being on "brilliant" paper, whatever that may be.

The HKPS says the 1975 set had a new watermark:

http://hkpsociety.com/?page_id=121

[halfgweilo]

Many thanks for your quick response. You've been a great help indeed. It's true to say 'Live is wonderful'.