There may be some significance in the fact that the globe is unmarked as to RR name. I know that repro globes are available in various colors. I own some D&RG and D&RGW lanterns (although, admittedly, none have green globes, and are Adams and Westlake or Adlake manufacture rather than Dressel). All have marked globes, either cast or etched. This isn't to say that the Rio Grande did not use unmarked globes, but it seems to me that it would be difficult to verify that it is a D&RGW globe without the markings.