The four basic factors that determine the value of a marble ...
The most important determinant of marble value is the rarity of the type. The Marble Collectors Society of America classifies marbles by the following categories: Handmade Glass Marbles, Handmade Non-Glass Marbles, Machine-Made Marbles, and Contemporary Handmade Marbles.
This will serve as a guide to their relative rarity. However, rarity is not necessarily an indicator of price. A marble can be so rare that it is unrecognized by most collectors, and have a low price because of low demand. The hobby of marble collecting has also not reached maturity. As a result, the price structure at the high end of the market is quite compressed. The relation between rarity and price is not linear. This means that just because one particular marble is 100 times rarer than another particular type, it is not going to sell for 100 times more. The multiple will tend to be much less. If you encounter unfamiliar terms while browsing this site, check our marble glossary.
The second factor that determines the value of a marble is its condition. The grading of condition is very subjective. Every collector has their own opinion and no two collectors will ever agree on the exact condition of a particular marble. The Marble Collectors Society of America uses a descriptive grading system (Mint, Near Mint, Good, Collectible), which allows for some flexibility in grading. A numerical grading system based on a scale of 1 to 10 has also developed among marble collectors. The descriptions of each grading label used by the Society, along with the equivalent numerical grading is:
Mint: A marble that is in original condition. The surface is unmarked and undamaged. There may be some minor rubbing on the surface, however, the marble is just the way it came from the factory. (10.0-9.0)
Near Mint: A marble that has seen minor usage. There may be evidence of some hit marks, usually tiny subsurface moons, pinprick chips, tiny flakes or tiny bruises. The damage is inconsequential and does not detract from viewing the marble. If there is noticeable damage, then it is on only one side of the marble and the other side is Mint. (8.9-8.0)
Good: A marble that has seen usage. It will have numerous hit marks, subsurface moons, chips, flakes or bruises. The core can still be seen clearly, but the marble has obviously been used. If the damage is large or deep, then it is confined to one side and the other side is Mint to Near Mint. (7.9-7.0).
Collectible: A marble that has seen significant usage. Overall moons, chips, flakes and bruises. The core is completely obscured in some spots. A Collectible marble has served its purpose and been well used. Still, it is a placeholder in a collection until a better example comes along. (6.9-0.0).
Any damage to the surface of a marble, no matter how slight, will affect its value. For a given amount of damage, the depreciation of value is much greater for machine-made marbles than for handmade marbles. Even a small chip will effectively reduce the value of a machine-made marble by more than half. Collectors tend to be more forgiving of damage to a handmade marble, probably because handmade marbles are more difficult to find. Be wary of any marble that looks as if it may have been repaired or re-worked.
The third factor that determines the value of a marble is its size. The size of a marble is measured by its diameter in inches. Marble manufacturers utilized a sieve system of measuring. Using a device that measured marbles in 1/16" increments, the smallest opening that the marble would fall through was the size. Because of this method, the marbles classified as one size by a manufacturer, could in fact vary by 3/64". It was technically impossible to produce a handmade glass marble in sizes greater than about 2-1/2" in diameter. The marble would sag and deform during the annealing process because of its weight. However, different types of marbles are more common in some sizes than others. Machine-made marbles are usually 1/2" to 3/4". This is because marble tournament regulations set the size of the shooters to be between 1/2" and 3/4" and the size of the target marbles to be 5/8". Again, the relative rarity of different sizes varies greatly from one type of marble to the next.
The final factor that determines the value of a marble is its eye appeal. Eye appeal is related to the brightness of the colors and the symmetry of the design. Brightly colored marbles command higher prices. Also, symmetrical or intricate designs tend to command higher prices. Keep in mind that eye appeal is very subjective, more so than condition. Thus, two collectors could value the same marble very differently.
There are no hard and fast rules for determining the value of a marble. You must take each of these four factors into consideration when valuing a marble and bear in mind that the value you decide may be far different from the value that the next collector comes up with.