Good point -- we may be making too much of the ad writer's marble knowledge / information. The words "cerise" and "prima," which are specific marble types we associate only with Peltier, could have been used in the ad in a more generic way -- probably without anyone complaining. Maybe Belkap Hardware was just using current "buzzwords," or trying to capitalize on the cerise and prima names? No mention of Peltier or Gropper. And I don't believe I'd characterize cerises as glass agates having "beautiful dark color combinations." And heck, the person who prepared the drawings and the person who prepared the copy were almost never the same people -- and of the two, the drawer may have been the only one with actual marbles to go by. If even he did. Most of the marble depictions in ads of this age look an awful lot alike.