Ron_W
1636
Thanks to your explanation i knew what to google for to learn more, and found this explanation and diagram
An Olive holed (hole with radius) ring jewel offers lower friction. The radius surface of the hole provides minimum contact with the pivot.
it seems the inside wall of the hole is curved , so less friction as there is less contact and more `room` for the oil to contact with the pivot.. So its is the hole that is shaped and not necessarily the jewel itself as i understand it now?
Next time on Trivial Pursuit i ll be nailing this one !