Comment 3 for bug 1482324

Macs will only give a proper name to a volume when it finds a HFS+ partition with a few OS X files.

Fedora ISOs include a HFS+ partition hidden to non-OS X platforms. It uses a method similar to how OS X Install DVDs manages to show the partition containing the OS X installer only on OS X while showing the partition containing Windows Bootcamp drivers on all other platforms.

In that HFS+ partition you'll need a /mach_kernel file (which can be empty) /System/Library/CoreServices/boot.efi (which can be a symlinked to GRUB located somewhere in /EFI), and /System/Library/CoreServices/SystemVersion.plist (just copy one from a Mac and change the description to Linux and elementary). The HFS+ partition doesn't need to be journaled.

With this partition, it also makes it possible to boot elementary OS from the OS X System Preferences Startup Disk panel.

I created and attached a higher res icns as pixel accurately as I was able to which goes all the 512x512 (with 10% padding on all sides).

I hope this helps.