We've seen Portal proposals and Portal jewelry before. But putting them together into a Companion Cube engagement ring is a new one on me.
The ring is stainless steel and, yes, the cube is a tiny exact replica with its little heart on every side. It was custom made by bmf jewelry for Justin Palmer, who did indeed propose by asking, "Will you be my partner in science?"
She said yes.
Portal Companion Cube Engagement Ring [Custom Made via The Mary Sue]