Decoding Benrus Watch Markings: Gold Filled & Date Identification

Question
On the flex-let band of a benrus ladies watch the markings are:-
One end: 1/20-10KOGF.TOP
Other end: 56-USA
I understand the markings.  My question is, can you tell the date from the information?  I believe 56 is the percentage purity of the gold, not 1956.

Answer
Michael, metal quality marks vary somewhat from country to country and I am not an expert on markings for other countries.  The precious metal markings for sterling, gold and platinum alloys are fairly clear cut in the UK and in the USA.   With gold filled, I am no so certain but the markings are USA markings, as the USA on the band would indicate unless marked for export.

The 56 has little to do with the percentage of pure gold in the gold layer.  This is why:
1/20 10KOGF.TOP tells me the band likely has a gold filled layer on a base metal band lower structure. Am I wrong in this assumption, sight unseen?

Regardless, the 1/20 means that 10k gold represents 1/20 by weight of the actual gold filled layer, an overlay I also suspect on the base of the band.  The 10k tells the purity of the gold. It is simply 10k(or 10ct in the UK).  This means 10 parts of 24 in the gold are pure gold and the rest of the metal mix is other metals. (24 is considered pure and karats are based on a system of 24 parts.)  10/24 = 0.4167, round off and decimal removed as would be seen on a jewelry stamp is 417, also the same as 41.7% gold in the alloy, not 56%.  56% would be 0.56 x 24 = 13.4k, higher by far than the 10kOGF indicates.

Can I tell the date from the information? No, I cannot. I suspect as do you that the 56 is not a date stamp but to me likely represents a band style or sub-style.

If you are curious about the date of the ladies watch, there are many good watch books with illustrations in abundance and details to use in identification of the watch.  The books are easy to use.

Michael, I could not provide the date.  Sorry about that.  The band may not be the same age as the watch if it is a removable sort but a replacement from more other years.

Best wishes. God Bless and Peace.  Thomas.