In New York members of a Dutch diamond firm concluded that some of The Netherlands’ skilled cutters had escaped to London and asked to ship cutting equipment.

In their rich, paneled offices off an awninged terrace overlooking the Hudson in downtown Manhattan, officials of the Dutch diamond firm of J. K. Smit & Sons were solemn last week. Amsterdam and their home office were in Nazi hands. So, too, they feared, were snow-haired Johan Smit, head of…