I bought these recently knowing exactly what they are - thought that I'd post them here as others may be interested. The sale is obviously wrong and my photography even worse than normal - but interesting I thought?
They are contemporary counterfeits in brass, which was lightly silver plated to pass off as the real thing - most of the plating is long gone. The penalties for such an activity then were less severe than in the 18th century - death, but still quite severe - transportation to the other side of the world to the land of the billabong.