Trying to identify a marble may make you, well, lose your marbles. Sometimes it can be nearly impossible to positively ID a particular marble, but there are ways you can narrow the possibilities. Identifying how the marble was made will tell you the most about its history, and whether it has any value. Many of the handmade marbles from Germany and some of the early manufactured marbles in the U.S. can be worth a pretty penny.
See if the marble has a pontil mark, which would be made from the rod used to blow the glass marble. This indicates the marble was handmade.
The handmade marbles made Germany up until about World War II feature latticino canes in a swirl. There are many different kinds of latticino swirls, which can be identified by the marble's center. A latticino core could indicate a handmade marble, while manufactured marbles likely will have a naked core or solid core.
Check the opacity of the glass. Many of the older marbles are opaque, not transparent, and lighting does not reveal the center.
Check the marble's construction. Is it actually glass? It could be stone or crockery, which may up its value.
See if there are any corkscrews in the glass. A corkscrew has an opaque swirl that runs completely around the marble from top to bottom. There are transparent and opaque swirls, too. A nicely corked marble was likely made by Akro Agate Co., which began making marbles in the U.S. in 1914.
Check if the marble has a flame design. Flames are usually older and collectible.
Check the condition of the marble, too. While identifying a marble, look with a magnifying glass to see if it has "eyelashes" or little dings. You will be surprised how much damage the older used marbles often have. Since condition is related to value, it is helpful to identify the condition along with the kind of marbles.