Are Mickey Mantle baseballs signed in green ink worth more money?

Answer 1

No. The bulk of the value of the signature will be determined on condition, how well the Baseball displays the signature, and how well the ink (color) stands out in contrast to the white baseball.

The signature should be strong, and bold, as opposed to faded and hard to see. In the case of a baseball Blue ballpoint pen would be most preferred by collectors over sharpie which tends bleed on a baseball, and has proven to hold up better over time than other inks.

The color ink would be a collectors preference on display, but there would be less collectors that would desire the green ink over the blue, and less demans, means less value. That is not to say that you cannot get full market value for the signature if it displays well.

If the signature is not properly authenticated the baseball could sell at half the market value or less. For more information on signed baseballs read my newsletter (link below) "How much Is My Autographed Baseball?