That's about as odd a denomination as you're going to see, isn't it?
This came out of a "junk" silver bin today, and so was purchased at just a small premium over melt.
The published specifications peg the diameter at 19 mm and the weight at 2.7 grams. This specimen measrues 18.7 mm and comes in at 2.65 grams.
There may be a small chop on the reverse.

