How do you value a marble?

Answer 1

In Eastern Europe, where children play more with marbles and less with expensive technological toys, there is often a value system for the most commonly circulated marbles. The most common type is completely transparent, with two colored streaks running through the glass. A marble with three streaks, or with artful thin streaks, is worth two "plain" ones. A white non-transparent marble called "bonja" in Croatian (pronounced bo-nya, origin unknown) is also worth two. A black bonja is usually worth between three and four plain ones, although they are more often traded for more valuable marbles, not less. A green non-transparent marble is among the rarest, and can fetch up to ten "plain" marbles but again most kids would use such a valuable asset to purchase something more luxurious-seeming than a large number of "plains." The most valuable marbles are "sunny" marbles. They are semi-transparent, of colored glass, most often red or brown, although green, blue and gray are also seen from time to time. They have tiny air bubbles embedded into the glass, and a widespread myth suggests that one can observe a solar eclipse through such a marble without suffering eye damage, hence the name.

Answer 2

They make a marble price guide. I don't know by who but I've seen it at my local Border's so I know it's out there.