The gemworld.zip file you have requested: Maps / Mission Maps / RA2 / Gemworld - 1.18mb is not available. Perhaps try browsing all files for the game C&C: Red Alert 2 and upload any files you want to share or are missing. This is the only information we could locate:
This is a nice, large 8-player-map (100 x 100). There are lots of buildings and your base is build on a cliff so you can defend your base very well. There are 4 isles with lots of gems for an total of +/- 860000 and there are 2 oilderricks on each isle. You don't have much ground for building a base so that makes the game a little harder.