Instructions
Identify any particularly common marbles. The most common of all is the "Leaf Insert" marble, adorned with a simple leaf-shaped core of colored glass. The "Cat's Eye," another widely seen marble, has a small multicolored core.
Look for clear glass marbles -- or "clears" -- patterned on the inside with deliberate stripes of color. These are known as "swirls." A swirl with added copper filings to make it glisten is called a "Lutz."
Turn to any opaque glass marbles decorated with stripes. Marbles with stripes over a creamy background are called "Clambroths." "Indian and Peppermint Swirls" are like the Clambroth except that the body of the marble contains at least some black glass.
Consider any marbles without a deliberate pattern. "Onionskins" are marbles with a mottled, multicolored surface. "Mica Snowflakes" have chips of mica suspended in clear glass. "Slag" and "End of Day" marbles are made from pieces of colored glass squashed together at random.