Ring Judgement

My fiance and I recently got engaged and I've been getting some pretty opinionated feedback about my ring. We are not a super traditional couple and he ended up not going with a traditional diamond ring, and instead the main stone is an opal. I am absolutely in love with the ring, but many of my friends and family members are giving pretty negative feedback about it. For example, "that's not a real engagement ring" or "oh so he couldn't afford a diamond, huh?".
I honestly don't really care if they like it or not, but it does tend to be a little offputting when they are being blatantly rude about it. How would you suggest dealing with a situation like this without coming across as a serious jerk?
I've attached a photo of the ring for reference.