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Gnome Disks utility is great, but it is no more "powerful" than OS X's disk utility, with the possibility of supporting more filesystems out of the box, which isn't really relevant since your SD card is probably some type of FAT, which both certainly support.
About all Gnome Disks does for data recovery is let you make disk images. Does your SD card show up in disk utility's GUI? Does it show up with "diskutil list" at the CLI? If it shows up in either of those, you can use OS X's disk utility to make a disk image of it, and try recovery (like photorec or testdisk) on a copy of the disk image, or if it's really important send either the card, the image, or both to a data recovery specialist.
Edit: Gnome Disks is written in C and licensed under the LGPL, so in theory, you could try to compile it under OSX if you'd like, I'm not aware of anyone that distributes binaries of it for OS X though, and I have no idea what the dependencies look like. Probably not realistic.