"Three 19th Century Billiard Balls"
And yes, they were already round at that time…. They measured 55 millimeters in diameter and were precisely shaped from a material that was very common at the time and which can no longer be used today. They were dyed and they have kept the trace of this in the veins of age. 
Le Magazine de PROANTIC
TRÉSORS Magazine
Rivista Artiquariato