When Things Are Similar But Different

[marble novice]

I need someone to explain to me what I'm looking at here (see links below). I have a few mibs, white base with colored ribbons around the center. In trying to figuring out who made them, I'm looking at

Peltier Rainbo

http://www.joemarble...any%2010-07.htm

and

Vitro Agate Whitie

http://www.joemarble...pany%203-13.htm

To me, they look pretty similar, but I do notice subtle differences. My primary challenge (this time ) is that I'm not totally clear on what makes those subtle differences -- is the base glass on one maker's marbles whiter than the other's? Is the ribbon more of a veneer on one, yet running deeper on the other's? Are the clues in the ribbon colors?

What are the telltale signs that make these and others like them different?

As always, thanks for letting me pick your brains.

Holly

[lstmmrbls]

rainbos are actually 4 streams on the marbles. 2 streams often bleed together making appear as one. Notice how they are always darker at the edge while whities will usually appear the same from edge to edge. That is also a much wider than normal band on that whitie.