Paul,
As a quick rule of thumb, anything with the original logo (pre 94) should have no laser etching on the lens, the blue frame you refer to sounds like one of the splatters, so thats fine, as does the Crystal Blue, but I have a concern about the dark green and silver frames you mention, and sadly think that they could be fake, as they didnt release those colourways.
Mumbo was only the intended original name until the clothing company Mambo thought it sounded too close to there name brand, so Jim decided to change it to avoid any issues.