Wow, I just scored over 300,000 in Classic Mode!
The description of the achievement is WRONG! You have to get 500.000 points in classic mode to unlock this achievement! You need to get to level 12 or 13 to reach the needed points. You can always use the TerreDactyl-method if you can't do it legit which will make this achievement a cakewalk! Quit to the main menu after each level and copy the save file ("C:/users/[yourusernamehere]/Appdata/local/packages/PopCap.BejweledLIVE_dw446q17t8sdy/localstate/classic.sav") to the desktop and try other matches if you fail.