For a much more thorough description of the history of hand made glass marbles, please visit my History of Glass Making in Lauscha, Germany page.
Transparent Swirls can be found in size from 7/16" to well over two inches, though some are more restricted in their size range. Several factors can increase the collectibility and therefore the value of Transparent Swirls.
There will be at least three and as many as six bands.
Naked examples, along with those possessing three levels, are rarer and therefore more collectible.
Examples with a left-hand twist are also more highly prized but often go undetected; these marbles have a twist to their design that goes to the right of the viewer, rather than to the left as is much more common.
The base glass is almost always clear and colorless, though tinted glass is found infrequently in shades of blue, green, or even amber.
Some Latticinio Swirls are "naked," that is, lacking an outer design.