Thank you very much! Yes, all the Ornament Mini Cards are 3"x3".
I've updated the details for this card and I will be upload the back of the card at some point.
The base is actually all Whisper White, but, I've covered the front and a part of the back with coloured cardstock. I covered part of the back because I wanted a "sealed" look on the sides and I only covered part of the back because I needed to conserve paper. I scalloped trimmed the edge at the back so it looked a little more polished.