Assuming you're using the original size/type of disk that you created the image from in the first place, and you already know the block size, here is the command (modify to your needs):
# unpigz myDiskImage.dd.gz | dd bs=512k of=/dev/sdi
To know the progress of the restoration, us pipe viewer like below:
# pv myDiskImage.dd.gz | unpigz | dd bs=512k of=/dev/sdd
