I think you're probably trying to describe the typical way of designating gold-fill on an old stretch band. They'll typically be marked 1/20th 10K (or 1/20th 14K, etc.) This means that the layer of gold (10K or 14K, etc.)surrounding the base metal of the band represents 1/20th of the weight of the piece.
If memory serves me correctly, I believe 1/20th of total content by weight is the lowest allowed gold percentage for a piece to be designated as gold-filled. Lower percentages would be called rolled gold plate (R.G.P.) or gold plated.
The bottom line is that there is very little gold content in those old stretch bands and they have very little value, either from a collectible standpoint or from gold content.
I also own a Kreisler band marked gold content .025 with Patent # U.S. PAT.2,064,760 which dates that to 1936. I believe that is the same gold content as 1/20 12k gold filled, or 2.5 % of the band weight (1/20 is .05 ; 12k/24K =50%; hence .05 x .50= .025).