A creative alternative to using the icon sets offered with conditional formatting is to use the various symbol fonts that come with Office. The symbol fonts are Wingdings, Wingdings2, Wingdings3, and Webdings. These fonts display symbols for each character instead of the standard numbers and letters.
The idea here is simple. Make a formula that returns a character, then change the font so that the symbol for that character is shown based on the font you select. For example, imagine you want to test if values in column A are greater than 50. You can enter the formula =IF(A1>50,”P”,”O”). In a standard font like Arial, this formula would return either a P or an O. However, if you would change the font to Windings2, you would see a check mark or an X.