Welcome to opalholicsanonymous.com where opal season lasts forever.

At least the new world is composed mostly of Calcium and Aluminum Oxides and they assume some in the form of Ruby or Sapphire, which could be any color of the rainbow depending on the minor elements there. If it was made I imagine it could have been broken up before and spread around to even become a meteorite here as the Diamond worlds could be pieces too. http://www.news.uzh.ch/en/articles/2018/Exoplanets.html

Science is amazing, when they get it right, but in this case, I would say rather that 'they surmise' that they're composed of those minerals, and 'believe that everything else they say based on observation' is correct, but until they can go there and actually prove it, it's still just an 'educated guess'.

Science is fluid, and always changing with the next theory, but the main issue I have with it is they base their estimations on how they see the universe works today, assuming the laws of the universe have always pretty much been the way they are now, but they weren't, and that's why so many theories eventually get tossed on the scrap heap. So although I hope they're correct, just because planets made of gemstones are a gemophile's dream, until they have proof I wouldn't try going there to mine them.

All kidding aside, that's an interesting one so thanks for posting it John. Way cool.