Yep. Download an old version, unzip it, and then download the “Graphene” folder inside that folder to your WordPress themes folder.
There are actually two folders involved here. The first one is called “Graphene – version number” and the one inside that is just called “graphene”. It’s the inside one that you want to upload, or else the theme won’t be available. This is how WP organizes things, including plugins. I think this actually throws a lot of people off.
But you might want to wait a few days to see if there is a 1.6 update available.